MPI – Troubleshooting
13-42
INSPECTION PROCEDURE 31 <EVOLUTION-IV>
Oxygen sensor system
Probable cause
When CO or HC concentration is too high, the malfunction of the parts shown at
right may be the cause.
D The oxygen sensor detects the density of oxygen in exhaust gas and inputs it
to the engine-ECU after converting into a voltage signal.
D The engine-ECU controls the fuel injection amount based on this signal such that
the stoichiometric air/fuel mixture ratio can be obtained.
D Malfunction of oxygen sensor
D Improper connector contact, open or short-circuited
harness wire
D Malfunction of engine-ECU
OK
Replace the engine-ECU.
Check the harness wire between
engine-ECU and oxygen sensor connector.
NG
Repair
NG
OK
Check trouble symptom.
OK
Replace the engine-ECU.
NG
Check the harness wire between
engine-ECU and oxygen sensor connector.
NG
Repair
OK
Check trouble symptom.
OK
Check the following connector: A-63
NG
Repair
OK
Measure at the oxygen sensor connector A-63.
D Disconnect the connector, and measure at the harness side.
D Continuity between 2 and earth
OK: Continuity
NG
Check the following connector: B-62
NG
Repair
Check the oxygen sensor. (Refer to P.13-32.)*
NG
Replace
NOTE
*: Refer to Workshop Manual for LANCER EVOLUTION-IV and EVOLUTION-V (Pub. No. S9806CNCP9).
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