Page 170 of 1496
Downloaded from www.Manualslib.com manuals search engine 1A-120 Engine General Information and Diagnosis:
DTC P0420: Catalyst System Efficiency below ThresholdS7RS0B1104046
System and Wiring Diagram
Circuit Description
ECM monitors oxygen concentration in the exhaust gas which has passed the warm up three way catalytic converter
by HO2S-2. When the catalyst is functioning properly, the variation cycle of HO2S-2 output voltage (oxygen
concentration) is slower than that of HO2S-1 output voltage because of the amount of oxygen in the exhaust gas
which has been stored in warm up three way catalytic converter.
Reference
Oscilloscope waveforms
C37-11
C37-10
C37-57
WHT
BRN
1
3 2
4
5 VYELYEL
BLUWHTBLUWHT 5
I4RS0A110037-01
1. HO2S-1
3. Warm up three way catalytic converter 5. ECM
2. HO2S-2 4. Three way catalytic converter
I2RH01110102-01
Page 171 of 1496

Downloaded from www.Manualslib.com manuals search engine Engine General Information and Diagnosis: 1A-121
DTC Detecting Condition and Trouble Area
DTC Confirmation Procedure
WARNING!
• When performing a road test, select a place where there is no traffic or possibility of a traffic accident and be very careful during testing to avoid occurrence of an accident.
• Road test should be carried out by 2 persons, a driver and a tester, on a level road.
NOTE
Check to make sure that following conditions ar e satisfied when using this “DTC Confirmation
Procedure”.
• Intake air temperature at engine start: –10 °C (14 ° F) to 80 °C (176 °F)
• Intake air temperature: –10 °C (14 °F) to 70 °C (158 °F)
• Engine coolant temp.: 70 °C, 158 °F to 150 °C (302 °F)
• Altitude (barometric pressure): 2400 m, 8000 ft or less (500 mmHg, 75 kPa or more)
1) Connect scan tool to DLC with ignition switch turned OFF.
2) Turn ON ignition switch and clear DTC using scan tool.
3) Increase vehicle speed to 37 – 62 mph, 60 – 100 km/h. (engine speed: 2500 – 3000 r/min.)
4) Keep above vehicle speed for 10 min. or more (Thr ottle valve opening is kept constant in this step).
5) Stop vehicle and check if DTC / pending DTC exists using sc an tool. If not, check if catalyst monitoring test has
been completed using scan tool. If not in both of above checks (i.e., no DTC / pending DTC and catalyst
monitoring test not completed), check vehicle cond ition (environmental) and repeat Step 3) through 5).
DTC Troubleshooting
NOTE
• When measuring circuit voltage, resistance and/ or pulse signal at ECM connector, connect the
special tool to ECM and/or the ECM connectors re ferring to “Inspection of ECM and Its Circuits”.
• Upon completion of inspection and repair work, perform “DTC Confirmation Procedure” and confirm that the trouble has been corrected.
DTC detecting condition Trouble area
Response delay of HO2S-2 signal (shifting delay from rich to lean and
from lean to rich with threshold at 0.45 V) compared to switching cycle
(rich-lean) of A/F feed back is less than specified while vehicle is
running at constant speed and except with high engine load after
warmed up.
(*2 driving cycle detection logic, monitoring once per driving cycle) • Exhaust gas leak
• Warm up three way catalytic converter
malfunction
• HO2S-2 malfunction
• HO2S-1 malfunction
Step Action YesNo
1 Was “Engine and Emission Control System Check”
performed? Go to Step 2.
Go to “Engine and
Emission Control
System Check”.
2 Exhaust system visual check
1) Check exhaust system for leaks, damage and loose
connection.
Is it in good condition? Go to Step 3.
Repair or replace
defective part.
Page 382 of 1496

Downloaded from www.Manualslib.com manuals search engine 1G-7 Fuel System:
Fuel Pressure Relief ProcedureS7RS0B1706003
CAUTION!
This work must not be done when engine is
hot. If done so, it may cause adverse effect to
catalyst.
NOTE
If ECM detects DTC(s) after servicing, clear
DTC(s) referring to “DTC Clearance in
Section 1A”.
1) Make sure that engine is cold.
2) Shift transaxle gear shift lever in “Neutral” (shift select lever in “P” range for A/T model), set parking
brake and block drive wheels.
3) Remove relay / fuse box cover.
4) Disconnect fuel pump relay (1) from relay / fuse box (2).
5) Remove fuel filter cap in order to release fuel vapor pressure in fuel tank, and then reinstall it.
6) Start engine and run it until engine stops for lack of fuel. Repeat cranking engine 2 – 3 times for about 3
seconds each time in order to dissipate fuel pressure
in lines. Fuel connections are now safe for servicing.
7) After servicing, connect fuel pump relay (1) to relay / fuse box and install re lay / fuse box cover.
Fuel Leakage Check ProcedureS7RS0B1706004
After performing any service on fuel system, check to
make sure that there are no fuel leakages as follows.
1) Turn ON ignition switch for 3 seconds (to operate fuel pump) and then turn it OFF.
Repeat this (ON and OFF) 3 or 4 times and apply
fuel pressure to fuel line until fuel pressure is felt by
hand placed on fuel feed hose.
2) In this state, check to see that there are no fuel leakages from any part of fuel system.
Fuel Lines On-Vehicle InspectionS7RS0B1706005
CAUTION!
Due to the fact that fuel feed line (1) is under
high pressure, use special care when
servicing it.
Visually inspect fuel lines for evidence of fuel leakage,
hose crack and deterioration or damage.
Make sure all cl amps are secure.
Replace parts as needed.
Fuel Pipe Removal and InstallationS7RS0B1706006
WARNING!
Before starting the following procedure, be
sure to observe “Precautions on Fuel System
Service” in order to reduce the risk or fire
and personal injury.
Removal
1) Relieve fuel pressure in fuel feed line according to “Fuel Pressure Relief Procedure”.
2) Disconnect negative cable at battery.
3) Disconnect fuel pipe joint and fuel hose (3) from fuel pipe (2) at the front and rear of each fuel pipe
referring to “Fuel Hose Disconnecting and
Reconnecting”.
4) Mark the location of clamps (1) on fuel pipes (2), so that the clamps can be reinstalled to where they
were.
5) Remove pipes (2) with clamp (1) from vehicle.
6) Remove clamp (1) from pipes (2).
1
I4RS0A170004-01
1
I4RS0A170005-01
2
13
I4RS0A170020-01
Page 424 of 1496

Downloaded from www.Manualslib.com manuals search engine 1K-1 Exhaust System:
Engine
Exhaust System
General Description
Exhaust System DescriptionS7RS0B1B01001
The exhaust system consists of an exhaust manifold, three-way catalytic converter (TWC) in catalyst case, exhaust
pipes, a muffler and seals, gasket and etc.
The three-way catalytic converter is an emission control device added to the exhaust system to lower the levels of
Hydrocarbon (HC), Carbon Monoxide (CO), and Oxides of Nitrogen (NOx) pollutants in the exhaust gas.
Diagnostic Information and Procedures
Exhaust System CheckS7RS0B1B04001
WARNING!
To avoid the danger of being burned, do not touch the exhaust system when the system is hot. Any
service on the exhaust system should be performed when the system is cool.
At every interval of periodic maintenance service, and when vehicle is raised for other service, check exhaust system
as follows:
• Check rubber mountings for damage, deterioration, and out of position.
• Check exhaust system for leakage, loose connection, dent and damage.
• If bolts or nuts are loosened, tighten them to specified torque referring to “Exhaust System Components”.
• Check nearby body areas damaged, missing, or mispositio ned part, open seam, hole connection or any other
defect which could permit exhaust fumes to seep into vehicle.
• Make sure that exhaust system components have enough clearance from underbody to avoid overheating and
possible damage to passenger compartment carpet.
• Any defect should be fixed at once.
IYSY011B0003-01