2004 DAEWOO LACETTI heater fan

SECTION : 1D
ENGINE COOLING
CAUTION : Disconnect the negative battery cable before removing or installing any electrical unit or when a tool
or equipment could easily come in contact with exposed electrical terminals. Disconnecting this cable will help
prevent personal injury and damage to the vehicle. The ignition must also be in LOCK unless otherwise noted.
TABLE OF CONTENTS
SPECIFICATIONS1D–2 . . . . . . . . . . . . . . . . . . . . . . . . . .
Capacity 1D–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fastener Tightening Specifications 1D–2. . . . . . . . . . .
SPECIAL TOOLS1D–2 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Special Tools Table 1D–2. . . . . . . . . . . . . . . . . . . . . . . .
DIAGNOSIS1D–3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Thermostat Test 1D–3. . . . . . . . . . . . . . . . . . . . . . . . . . .
Surge Tank Cap Test 1D–3. . . . . . . . . . . . . . . . . . . . . . .
Cooling System Diagnosis 1D–4. . . . . . . . . . . . . . . . . .
COMPONENT LOCATOR1D–5 . . . . . . . . . . . . . . . . . . . .
Radiator/Fan 1D–5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Water Pump/Thermostat (1.4L/1.6L DOHC) 1D–6. . .
Water Pump/Thermostat (1.8L DOHC) 1D–7. . . . . . .
MAINTENANCE AND REPAIR1D–8 . . . . . . . . . . . . . . .
ON–VEHICLE SERVICE 1D–8. . . . . . . . . . . . . . . . . . . . . Draining and Refilling the Cooling System 1D–8. . . . .
Thermostat (1.4L/1.6L DOHC) 1D–9. . . . . . . . . . . . . . .
Thermostat (1.8L DOHC) 1D–10. . . . . . . . . . . . . . . . . .
Water Pump 1D–11. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electric Cooling Fan – Main or Auxiliary 1D–13. . . . . .
Surge Tank 1D–14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Radiator 1D–16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
GENERAL DESCRIPTION AND SYSTEM
OPERATION1D–18 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General Description 1D–18. . . . . . . . . . . . . . . . . . . . . . .
Radiator 1D–18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Surge Tank 1D–18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Water Pump 1D–18. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Thermostat 1D–18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electric Cooling Fan 1D–19. . . . . . . . . . . . . . . . . . . . . . .
Engine Block Heater 1D–19. . . . . . . . . . . . . . . . . . . . . .

1D – 4IENGINE COOLING
DAEWOO V–121 BL4
COOLING SYSTEM DIAGNOSIS
Engine Overheats
ChecksAction
Check for a loss of the coolant.Add the coolant.
Check for a weak coolant solution.Confirm that the coolant solution is a 50/50 mixture of eth-
ylene glycol and water.
Check the front of the radiator for any dirt, any leaves, or
any insects.Clean the front of the radiator.
Check for leakage from the hoses, the coolant pump, the
heater, the thermostat housing, the radiator, the core
plugs, or the head gasket.Replace any damaged components.
Check for a faulty thermostat.Replace a damaged thermostat.
Check for retarded ignition timing.Perform an ECM code diagnosis. Confirm the integrity of
the timing belt.
Check for an improperly operating electric cooling fan.Replace the electric cooling fan.
Check for radiator hoses that are plugged or rotted.Replace any damaged radiator hoses.
Check for a faulty water pump.Replace a faulty water pump.
Check for a faulty surge tank cap.Replace a faulty surge tank cap.
Check for a cylinder head or an engine block that is
cracked or plugged.Repair the damaged cylinder head or the damaged engine
block.
Loss of Coolant
ChecksAction
Check for a leak in the radiator.Replace a damaged radiator.
Check for a leak in the following locations:
S Surge tank.
S Hose.Replace the following parts, as needed:
S Surge tank.
S Hose.
Check for loose or damaged radiator hoses, heater hoses,
and connections.Reseat the hoses.
Replace the hoses or the clamps.
Check for leaks in the coolant pump seal.Replace the coolant pump seal.
Check for leaks in the coolant pump gasket.Replace the coolant pump gasket.
Check for an improper cylinder head torque.Tighten the cylinder head bolts to specifications.
Replace the cylinder head gasket, if needed.
Check for leaks in the following locations:
S Intake manifold.
S Cylinder head gasket.
S Cylinder block plug.
S Heater core.
S Radiator drain plug.Repair or replace any components, as needed, to correct
the leak.
Engine Fails to Reach Normal Operating Temperature or Cool Air
from the Heater
ChecksAction
Check to determine if the thermostat is stuck open or is the
wrong type of thermostat.Install a new thermostat of the correct type and heat range.
Check the coolant level to determine if it is below the MIN
mark on the surge tank.Add sufficient coolant to raise the fluid to the specified
mark on the surge tank.

1D – 18IENGINE COOLING
DAEWOO V–121 BL4
GENERAL DESCRIPTION
AND SYSTEM OPERATION
GENERAL DESCRIPTION
The cooling system maintains the engine temperature at
an efficient level during all engine operating conditions.
When the engine is cold, the cooling system cools the en-
gine slowly or not at all. This slow cooling of the engine al-
lows the engine to warm up quickly.
The cooling system includes a radiator and recovery sub-
system, cooling fans, a thermostat and housing, a coolant
pump, and a coolant pump drive belt. The timing belt
drives the coolant pump.
All components must function properly in order for the
cooling system to operate. The coolant pump draws the
coolant from the radiator. The coolant then circulates
through water jackets in the engine block, the intake man-
ifold, and the cylinder head. When the coolant reaches the
operating temperature of the thermostat, the thermostat
opens. The coolant then goes back to the radiator where
it cools.
This system directs some coolant through the hoses to the
heater core. This provides for heating and defrosting. The
surge tank is connected to the radiator to recover the cool-
ant displaced by expansion from the high temperatures.
The surge tank maintains the correct coolant level.
The cooling system for this vehicle has no radiator cap or
filler neck. The coolant is added to the cooling system
through the surge tank.
RADIATOR
This vehicle has a lightweight tube–and–fin aluminum ra-
diator. Plastic tanks are mounted on the right and the left
sides of the radiator core.
On vehicles equipped with automatic transaxles, the
transaxle fluid cooler lines run through the left radiator
tank. A radiator drain cock is on this radiator.
To drain the cooling system, open the drain cock.
SURGE TANK
The surge tank is a transparent plastic reservoir, similar to
the windshield washer reservoir.
The surge tank is connected to the radiator by a hose and
to the engine cooling system by another hose. As the ve-
hicle is driven, the engine coolant heats and expands. The
portion of the engine coolant displaced by this expansion
flows from the radiator and the engine into the surge tank.
The air trapped in the radiator and the engine is degassed
into the surge tank.When the engine stops, the engine coolant cools and con-
tracts. The displaced engine coolant is then drawn back
into the radiator and the engine. This keeps the radiator
filled with the coolant to the desired level at all times and
increases the cooling efficiency.
Maintain the coolant level between the MIN and the MAX
marks on the surge tank when the system is cold.
WATER PUMP
The belt–driven centrifugal water pump consists of an im-
peller, a drive shaft, and a belt pulley. The water pump is
mounted on the front of the transverse–mounted engine,
and is driven by the timing belt.
The impeller is supported by a completely sealed bearing.
The water pump is serviced as an assembly and, there-
fore, cannot be disassembled.
THERMOSTAT
A wax pellet–type thermostat controls the flow of the en-
gine coolant through the engine cooling system. The ther-
mostat is mounted in the thermostat housing to the front
of the cylinder head.
The thermostat stops the flow of the engine coolant from
the engine to the radiator in order to provide faster warm–
up, and to regulate the coolant temperature. The thermo-
stat remains closed while the engine coolant is cold, pre-
venting circulation of the engine coolant through the
radiator. At this point, the engine coolant is allowed to cir-
culate only throughout the heater core to warm it quickly
and evenly.
As the engine warms, the thermostat opens. This allows
the engine coolant to flow through the radiator, where the
heat is dissipated through the radiator. This opening and
closing of the thermostat permits enough engine coolant
to enter the radiator to keep the engine within proper en-
gine temperature operating limits.
The wax pellet in the thermostat is hermetically sealed in
a metal case. The wax element of the thermostat expands
when it is heated and contracts when it is cooled.
As the vehicle is driven and the engine warms, the engine
coolant temperature increases. When the engine coolant
reaches a specified temperature, the wax pellet element
in the thermostat expands and exerts pressure against the
metal case, forcing the valve open. This allows the engine
coolant to flow through the engine cooling system and cool
the engine.
As the wax pellet cools, the contraction allows a spring to
close the valve.
The thermostat begins to open at 87°C (189°F) and is fully
open at 102°C (216°F). The thermostat closes at 86°C
(187°F).

ENGINE COOLING 1D – 19
DAEWOO V–121 BL4
ELECTRIC COOLING FAN
CAUTION : Keep hands, tools, and clothing away
from the engine cooling fans to help prevent personal
injury. This fan is electric and can turn ON whether or
not the engine is running.
CAUTION : If a fan blade is bent or damaged in any
way, no attempt should be made to repair or reuse the
damaged part. A bent or damaged fan assembly
should always be replaced with a new one. Failure to
do so can result in personal injury.
The cooling fans are mounted behind the radiator in the
engine compartment. The electric cooling fans increase
the flow of air across the radiator fins and across the con-
denser on air condition (A/C)–equipped vehicles. This
helps to speed cooling when the vehicle is at idle or moving
at low speeds.
1.4L DOHC engine fan size is 340mm (13.4 in.) and
1.6L/1.8L DOHC engine main fan size is 300 mm (11.8
inches) in diameter with five blades to aid the air flow
through the radiator and the condenser. An electric motor
attached to the radiator support drives the fan.
A/C models have two fans – the main fan and the auxiliary
fan. The auxiliary fan is 300 mm (11.8 inches) in diameter.
Non–A/C models have only the main fan.
A/C OFF or Non–A/C Model (1.4L/1.6L)
S The cooling fans are actuated by the electronic
control module (ECM) using a low–speed cooling
fan relay and a high–speed cooling fan relay. On
A/C–equipped vehicles, a series/parallel cooling fan
relay is also used.
S The ECM will turn the cooling fans on at low speed
when the coolant temperature reaches 97.5°C
(207.5°F) and the cooling fans off at 95.25°C
(203.4°F).
A/C OFF or Non–A/C Model (1.8L)
S The cooling fans are actuated by the electronic
control module (ECM) using a low–speed cooling
fan relay and a high–speed cooling fan relay. On
A/C–equipped vehicles, a series/parallel cooling fan
relay is also used.
S The ECM will turn the cooling fans on at low speed
when the coolant temperature reaches 93°C
(199°F) and the cooling fans off at 90°C (194°F).
A/C ON (1.4L/1.6L)
S The ECM will turn the cooling fans on at low speed
when the A/C system is on. The ECM will change
to high speed when the coolant temperature reach-
es 101.25°C (214°F) or the high side A/C pressure
reaches 1859 kPa (270 psi).
S The cooling fans will return to low speed when the
coolant temperature reaches 99°C (210°F) and the
high side A/C pressure reaches 1449 kPa (210 psi).
A/C ON (1.8L)
S The ECM will turn the cooling fans on at low speed
when the A/C system is on. The ECM will change
to high speed when the coolant temperature reach-
es 97°C (207°F) or the high side A/C pressure
reaches 1859 kPa (270 psi).
S The cooling fans will return to low speed when the
coolant temperature reaches 94°C (201°F) and the
high side A/C pressure reaches 1449 kPa (210 psi).
ENGINE BLOCK HEATER
The vehicle is designed to accept an engine block heater
that helps to warm the engine and to improve starting in
cold weather. It also can help to reduce fuel consumption
while a cold engine warms up.
The engine block heater is located under the intake man-
ifold and uses an existing expansion plug for installation.

1F – 2IENGINE CONTROLS
DAEWOO V–121 BL4
TROUBLE CODE DIAGNOSIS
(1.4L/1.6L DOHC) 1F–111. . . . . . . . . . . . . . . . . . . . . . . .
Clearing Trouble Codes 1F–111. . . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Codes (1.4L/1.6L DOHC) 1F–111.
DTC P0107 Manifold Absolute Pressure Sensor
Low Voltage 1F–114. . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0108 Manifold Absolute Pressure Sensor
High Voltage 1F–117. . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0112 Intake Air Temperature Sensor Low
Voltage 1F–120. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0113 Intake Air Temperature Sensor High
Voltage 1F–122. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0117 Engine Coolant Temperature
Sensor Low Voltage 1F–125. . . . . . . . . . . . . . . . . . . .
DTC P0118 Engine Coolant Temperature
Sensor High Voltage 1F–128. . . . . . . . . . . . . . . . . . . .
DTC P0122 Throttle Position Sensor Low
Voltage 1F–131. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0123 Throttle Position Sensor High
Voltage 1F–134. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0131 Front Heated Oxygen Sensor Low
Voltage 1F–137. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0132 Front Heated Oxygen Sensor High
Voltage 1F–140. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0133 Front Heated Oxygen Sensor No
Activity 1F–142. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0135 Front Heated Oxygen Sensor Heater
Circuit Not Functioning 1F–145. . . . . . . . . . . . . . . . . .
DTC P0137 Rear Heated Oxygen Sensor Low
Voltage 1F–148. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0138 Rear Heated Oxygen Sensor High
Voltage 1F–151. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0140 Rear Heated Oxygen Sensor No
Activity 1F–153. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0141 Rear Heated Oxygen Sensor Heater
Malfunction 1F–156. . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0171 Fuel Trim System Too Lean 1F–158. . . .
DTC P0172 Fuel Trim System Too Rich 1F–162. . . . .
DTC P0222 Main Throttle Idle Actuator (MTIA)
Low Voltage 1F–165. . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0223 Main Throttle Idle Actuator (MTIA)
High Voltage 1F–168. . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0261 Injector 1 Low Voltage 1F–171. . . . . . . . .
DTC P0262 Injector 1 High Voltage 1F–173. . . . . . . .
DTC P0264 Injector 2 Low Voltage 1F–175. . . . . . . . .
DTC P0265 Injector 2 High Voltage 1F–177. . . . . . . .
DTC P0267 Injector 3 Low Voltage 1F–179. . . . . . . . .
DTC P0268 Injector 3 High Voltage 1F–181. . . . . . . .
DTC P0270 Injector 4 Low Voltage 1F–183. . . . . . . . .
DTC P0271 Injector 4 High Voltage 1F–185. . . . . . . . DTC P0300 Multiple Cylinder Misfire(Catalyst
Damage) 1F–188. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0300 Multiple Cylinder Misfire(Increase
Emission) 1F–192. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0327 Knock Sensor Circuit Fault
(1.4L DOHC) 1F–195. . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0327 Knock Sensor Circuit Fault
(1.6L DOHC) 1F–198. . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0335 Magnetic Crankshaft Position
Sensor Electrical Error 1F–201. . . . . . . . . . . . . . . . . .
DTC P0336 58X Crankshaft Position Sensor
No Plausible Signal 1F–204. . . . . . . . . . . . . . . . . . . .
DTC P0337 58X Crankshaft Position Sensor
No Signal 1F–207. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0341 Camshaft Position Sensor
Rationality 1F–210. . . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0342 Camshaft Position Sensor Signal 1F–212
DTC P0351 Ignition Signal Coil A Fault 1F–214. . . . .
DTC P0352 Ignition Signal Coil B Fault 1F–216. . . . .
DTC P0400 Exhaust Gas Recirculation Out
Of Limit 1F–218. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0404 Exhaust Gas Recirculation
Opened 1F–221. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0405 EGR Pintle Position Sensor Low
Voltage 1F–224. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0406 EGR Pintle Position Sensor High
Voltage 1F–227. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0420 Catalyst Low Efficiency 1F–230. . . . . . . .
DTC P0444 EVAP Purge Control Circuit No
Signal 1F–232. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0445 EVAP Purge Control Circuit Fault 1F–235
DTC P0462 Fuel Level Sensor Low Voltage
(1.6L DOHC Only) 1F–238. . . . . . . . . . . . . . . . . . . . .
DTC P0463 Fuel Level Sensor High Voltage
(1.6L DOHC Only) 1F–241. . . . . . . . . . . . . . . . . . . . .
DTC P0480 Low Speed Cooling Fan Relay
Circuit Fault (1.4L DOHC) 1F–245. . . . . . . . . . . . . . .
DTC P0480 Low Speed Cooling Fan Relay
Circuit Fault (1.6L DOHC) 1F–248. . . . . . . . . . . . . . .
DTC P0481 High Speed Cooling Fan Relay
Circuit Fault (1.4L DOHC) 1F–251. . . . . . . . . . . . . . .
DTC P0481 High Speed Cooling Fan Relay
Circuit Fault (1.6L DOHC) 1F–254. . . . . . . . . . . . . . .
DTC P0501 Vehicle Speed No Signal
(M/T Only) 1F–257. . . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0510 Throttle Position Switch Circuit Fault
(1.4L DOHC) 1F–260. . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0510 Throttle Position Switch Circuit
Fault (1.6L DOHC) 1F–262. . . . . . . . . . . . . . . . . . . . .
DTC P0532 A/C Pressure Sensor Low Voltage 1F–264
DTC P0533 A/C Pressure Sensor High
Voltage 1F–267. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1F – 156IENGINE CONTROLS
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0141
REAR HEATED OXYGEN SENSOR HEATER
MALFUNCTION
Circuit Description
The engine control module (ECM) supplies a voltage of
about 450mm volts between the ECM terminals 14 and 16.
The oxygen (O2) sensor varies the voltage within a range
of about 1volt if the exhaust is rich, down to about 100mm
volts if the exhaust is lean. The O2 sensor is like an open
circuit and produces no voltage when it is below
360°C(600°F). An open O2 sensor circuit or a cold O2
sensor causes ”open loop” operation.
Conditions for Setting the DTC
S The heated O2 sensor heater resistance is less
than 0 W or greater than 160 W. (1.4L DOHC)
S The heated O2 sensor heater resistance is less
than 10 W or greater than 30 W. (1.6L DOHC)
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will illuminate
after three consecutive trip with a fail.
S The ECM will record operating conditions at the
time the diagnostic fail. This information will be
stored in the Freeze Frame and Failure Records
buffers.
S A history DTC is stored.S The coolant fan turns ON.
Conditions for Clearing the MIL/DTC
S The MIL will turn off after four consecutive ignition
cycles in which the diagnostic runs without a fault.
S A history DTC will clear after 40 consecutive warm
up cycles without a fault.
S DTC(s) can be cleared by using the scan tool.
S Disconnecting the ECM battery feed for 10 sec-
onds.
Diagnostic Aids
S Normal scan tool voltage varies between 0.1volts
and 0.9 volts while in closed loop.
S Inspect the oxygen (O2) sensor wire. The O2 sen-
sor may be positioned incorrectly and contacting
the exhaust manifold.
S Check for an intermittent ground in the wire be-
tween the O2 sensor and the engine control mod-
ule.
S Perform an injector 2alance test to determine if a
restricted fuel injector may be causing the lean con-
dition.
S Vacuum of crankcase leaks will cause a lean run-
ning condition.

1F – 230IENGINE CONTROLS
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0420
CATALYST LOW EFFICIENCY
Circuit Description
In order to control exhaust emissions of Hydrocarbons
(HC), Carbon Monoxide (CO) and Nitrogen Oxide (NOx),
a Three–Way Catalytic Converter (TWC) is used. The cat-
alyst within the converter promotes a chemical reaction
which oxidizes the HC and CO present in the exhaust gas,
converting them into harmless water vapor and carbon
dioxide, it also reduces NOx, converting it into nitrogen.
The catalytic converter also has the ability to store oxygen.
The Engine Control Module (ECM) has the capability to
monitor this process using a Heated Oxygen Sensor
(HO2S) located in the exhaust stream past the TWC. The
HO2S produces an output signal which indicates the oxy-
gen storage capacity of the catalyst; this in turn indicates
the catalyst’s ability to convert exhaust emissions effec-
tively. The ECM monitors the catalyst efficiency by first al-
lowing the catalyst to heat up, waiting for a stabilization pe-
riod while the engine is idling, and then adding and
removing fuel while monitoring the reaction of the HO2S.
When the catalyst is functioning properly, the HO2S re-
sponse to the extra fuel is slow compared to the Oxygen
Sensor (O2S). When the HO2S response is close to that
of the O2S, the Oxygen storage capability or efficiency of
the catalyst is considered to be bad, and the Malfunction
Indicator Lamp (MIL) will illuminate.
Conditions for Setting the DTC
S Closed loop stoichiometry.
S Engine Coolant Temperature (ECT) is more than
75°C (167°F) . (1.4L DOHC)
S Engine Coolant Temperature (ECT) is more than
70°C (158°F) . (1.6L DOHC)
S Engine speed between 1,766rpm and 2,368rpm.
(1.4L DOHC)
S Engine speed between 1,760rpm and 2,530rpm.
(1.6L DOHC)
S Vehicle speed is between 47km/h (29.2mph) and
80km/h (49.7mph). (1.4L DOHC)
S Vehicle speed is between 60km/h (37.3mph) and
76km/h (47.2mph). (1.6L DOHC)
S The manifold absolute pressure is greater than 70
kpa. (1.4L DOHC)S The manifold absolute pressure is greater than 76
kpa. (1.6L DOHC)
S Activity of the heated oxygen sensor excited by
lambda controller stimuli higher than a threshold.
S DTC(s) P0107, P0108, P0117, P0118, P0122,
P0123, P0131, P0132, P0133, P0137, P0138,
P0140, P0141, P0171, P0172, P0300, P0336,
P0337, P0341, P0342, P0351, P0352, P0404,
P0405, P0405 and P0562 are not sets.
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will illuminate
after three consecutive trip with a fail.
S The ECM will record operating conditions at the
time the diagnostic fail. This information will be
stored in the Freeze Frame and Failure Records
buffers.
S A history DTC is stored.
Conditions for Clearing the MIL/DTC
S The MIL will turn off after four consecutive ignition
cycles in which the diagnostic runs without a fault.
S A history DTC will clear after 40 consecutive warm–
up cycles without a fault.
S DTC(s) can be cleared by using the scan tool.
S Disconnecting the ECM battery feed for more than
10 seconds.
Diagnostic Aids
The catalyst test may abort due to a change in the engine
load. Do not change the engine load (i.e. A/C, coolant fan,
heater motor) while a catalyst test is in progress.
An intermittent problem may be caused by a poor connec-
tion, rubbed–through wire insulation, or a wire that is bro-
ken inside the insulation.
Any circuitry, that is suspected as causing the intermittent
complaint, should be thoroughly checked for the following
conditions:
S Backed–out terminals
S Improper mating
S Broken locks
S Improperly formed
S Damaged terminals
S Poor terminal–to–wire connection.

1F – 484IENGINE CONTROLS
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P0420
CATALYST OXYGEN SENSOR LOW EFFICIENCY
Circuit Description
In order to control exhaust emissions of Hydrocarbons
(HC), Carbon Monoxide (CO) and Nitrogen Oxide (NOx),
a Three–Way Catalytic Converter (TWC) is used. The cat-
alyst within the converter promotes a chemical reaction
which oxidizes the HC and CO present in the exhaust gas,
converting them into harmless water vapor and carbon
dioxide, it also reduces NOx, converting it into nitrogen.
The catalytic converter also has the ability to store oxygen.
The Engine Control Module (ECM) has the capability to
monitor this process using a Heated
Rear Heated Oxygen Sensor (HO2S2) located in the ex-
haust stream past the TWC. The HO2S2 produces an out-
put signal which indicates the oxygen storage capacity of
the catalyst; this in turn indicates the catalyst’s ability to
convert exhaust emissions effectively. The ECM monitors
the catalyst efficiency by first allowing the catalyst to heat
up, waiting for a stabilization period while the engine is id-
ling, and then adding and removing fuel while monitoring
the reaction of the HO2S2. When the catalyst is function-
ing properly, the HO2S2 response to the extra fuel is slow
compared to the Front Heated Oxygen Sensor (HO2S1).
When the HO2S2 response is close to that of the HO2S1,
the Oxygen storage capability or efficiency of the catalyst
is considered to be bad, and the Malfunction Indicator
Lamp (MIL) will illuminate.
Conditions for Setting the DTC
S Oxygen storage capacity index time is less than 0.3
seconds.
S Before idle test, the vehicle needs to be driven for
at least:
S 15 seconds at airflow is greater than 9.2 g/sec.
for manual transaxle.
S 11 seconds at airflow is greater than 12 g/sec
for automatic transaxle.
S Oxygen Sensor Capacity test condition:
S Closed loop stoichiometry.
S Purge concentration learned.
S Engine is running more than 330 seconds.
S Airflow is between 2.5 and 7.25 g/sec.
S Throttle Position (TP) sensor is less than 1.5%.
S Intake Air Temperature (IAT) is between –7°C
(19.4°F) and 105°C (221°F).
S Barometric pressure (BARO) is greater than 72 kPa
(10.4 psi).
S Catalyst temperature is between 500°C (932°F)
and 850°C (1562°F) for automatic transaxle.
S Catalyst temperature is between 450°C (842°F)
and 850°C (1562°F) for automatic transaxle.
S Closed Loop integrator change is less than 0.03.
S Idle time is less than 1 minute.
S Vehicle speed is less than 3 km/h (1.9 mph).S Block Learn Mode is learned.
S Above condition is stabilized for 5 seconds.
Note : Test is aborted for this idle if:
S Change in engine speed is greater than 80 rpm.
S A/C status changed.
S Cooling fan status changed.
S Insufficient air/fuel shift.
S DTC(s) P0106, P0107, P0108, P0117, P0118,
P0122, P0123, P0131, P0132, P0133, P1133,
P0134, P0135, P0137, P0138, P0140, P0141,
P1167, P1171, P0171, P0172, P0201, P0202,
P0203, P0204, P0300, P0336, P0337, P0341,
P0342, P0351, P0352, P0402, P0404, P1404,
P0405, P0406, P0443, P0502, P0506, P0507, and
P0562 are not set.
Action Taken When the DTC Sets
S The Malfunction Indicator Lamp (MIL) will illumi-
nate.
S The ECM will record operating conditions at the
time the diagnostic fails. This information will be
stored in the Freeze Frame and Failure Records
buffers.
S A history DTC is stored.
Conditions for Clearing the MIL/DTC
S The MIL will turn off after four consecutive ignition
cycles in which the diagnostic runs without a fault.
S A history DTC will clear after 40 consecutive warm–
up cycles without a fault.
S DTC(s) can be cleared by using the scan tool.
S Disconnecting the ECM battery feed for more than
10 seconds.
Diagnostic Aids
The catalyst test may abort due to a change in the engine
load. Do not change the engine load (i.e. A/C, coolant fan,
heater motor) while a catalyst test is in progress.
An intermittent problem may be caused by a poor connec-
tion, rubbed–through wire insulation, or a wire that is bro-
ken inside the insulation.
Any circuitry, that is suspected as causing the intermittent
complaint, should be thoroughly checked for the following
conditions:
S Backed–out terminals
S Improper mating
S Broken locks
S Improperly formed
S Damaged terminals
S Poor terminal–to–wire connection
Test Description
Number(s) below refer to the step number(s) on the Diag-
nostic Table.