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Rear oxygen sensor
Exhaust No.2Exhaust No.1Exhaust No.3
(main muffler)
UCCFront oxygen sensor
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1443-01
1. OVERVIEW
The ignition system is to supply high voltage generated from the ignition coil to the spark plug. The
G20DF engine is equipped with the independent type direct ignition system that the ignition coil is
installed in each cylinder.
The basic ignition timing in each cylinder is determined by the signals from camshaft position sensor and
crankshaft position sensor.
This ignition system controls the electronic ignition timing received from the engine ECU. To control the
ignition timing precisely, the ECU use the information below:
Engine load
Coolant temperature
Intake air temperature
Engine rpm
Camshaft position sensor (CPS)
Crankshaft position sensor (CKS) -
-
-
-
-
-
If the signal from the camshaft position sensor is not delivered to the engine ECU, the ignition coil and
fuel system cannot be operated.
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2. COMPONENTS
Ignition coil
Camshaft position
sensorKnock sensorInjector
Spark plug
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1443-01
Electric throttle valveT-MAP sensorAccelerator pedal position
sensor
Coolant temperature
sensor
Engine ECU
Crankshaft position
sensor
Page 514 of 1336

Problem Possible Cause Action
Coolant
level is too low
Coolant
temperature is
too high
2. INSPECTION
Leak from the radiator
Leak from the coolant auxiliary tank
Leak from the heater core -
-
-
Leak from the water inlet cap
Leak from the thermostat housing -
-Reconnect the hose or replace the
clamp
Change the hose -
- Leak from the coolant hose connections
Damaged coolant hose -
-
Change the gasket
Change the water pump -
- Leak from the water pump gasket
Leak from the water pump internal seal -
-
Tighten the bolts to the specified
torque
Change the cylinder head gasket -
- Incorrect tightening torque of the cylinder
head bolts
Damaged cylinder head gasket -
-Change the water inlet cap gasket
Change the thermostat sealing -
-
Coolant leakage (Coolant level is low)
Improper coolant mixture ratio
Kinked coolant hose -
-
-Add coolant
Check the coolant concentration
(Anti-freeze)
Repair or replace the hose -
-
-
Defective thermostat
Defective water pump
Defective radiator
Defective coolant auxiliary tank or tank
cap -
-
-
-Change the thermostat
Change the water pump
Change the radiator
Change the coolant auxiliary tank or
tank cap -
-
-
-Change the radiator
Change the coolant auxiliary tank
Change the heater -
-
-
Cracks on the cylinder block or
cylinder head
Clogged coolant passages in the
cylinder block or cylinder head -
-Change cylinder block or cylinder
head
Clean the coolant passage -
-
Clogged radiator core -
Replace the sensor or repair the
related wiring - Improper operation of cooling fan -Clean the radiator core -
Defective temperature sensor or faulty
wiring -Replace the cooling fan or repair the
related circuit -
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2112-01
Problem Possible Cause Action
Coolant
temperature is
too low
Thermostat is stuck open -
Replace the cooling fan or repair the
related circuit -
Improper operation of cooling fan -
Replace the sensor or repair the
related wiring -
Defective temperature sensor or faulty
wiring -Change the thermostat -
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2112-01
Coolant temperature
sensor
Measures the coolant
temperature and sends the result
to the engine ECU.
Radiator
Radiates the heat through fins and cools
down the hot coolant as the coolant
passes through the tube of the radiator
core.PWM fan
Circulates the fresh air forcibly to exchange
heat with the radiator core fin.
Coolant outlet port
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2112-01
Coolant outlet port
to radiator
to water pump (bypass)
to cabin heater
to coolant reservoir
Coolant temperature
sensor mountinh boss
from cylinder head
Gasket A:
B:
C:
D:
E:
F:
G:
Coolant outlet port