Diagnosis Procedure

1. Turn ignition switch OFF.
2. Check ground connection E9. Refer to Ground Inspection in Circuit Inspection .

Is the inspection result normal?

YES

GO TO 2.

NO

Repair or replace ground connection.

1. Clear the mixture ratio self-learning value. Refer to Description .
2. Run engine for at least 10 minutes at idle speed.

Is the 1st trip DTC P0171 or P0174 detected? Is it difficult to start engine?

YES

Perform trouble diagnosis for DTC P0171 or P0174. Refer to DTC Description .

NO

GO TO 3.

1. Turn ignition switch OFF.
2. Disconnect heated oxygen sensor 2 (HO2S2) harness connector.
3. Disconnect ECM harness connector.
4. Check the continuity between HO2S2 harness connector and ECM harness connector.

   DTC	HO2S2			ECM		Continuity
   	Bank	Connector	Terminal	Connector	Terminal
   P0137	1	F71	4	F79	99	Existed
   P0157	2	F70	4

5. Also check harness for short to power.

Is the inspection result normal?

YES

GO TO 4.

NO

Repair open circuit, short to ground or short to power in harness or connectors.

1. Check the continuity between HO2S2 harness connector and ECM harness connector.

   DTC	HO2S2			ECM		Continuity
   	Bank	Connector	Terminal	Connector	Terminal
   P0137	1	F71	3	F79	110	Existed
   P0157	2	F70	3		98

2. Check the continuity between HO2S2 harness connector and ground, or ECM harness connector and ground.

   DTC	HO2S2			--	Continuity
   	Bank	Connector	Terminal
   P0137	1	F71	3	Ground	Not existed
   P0157	2	F70	3

   DTC	HO2S2			--	Continuity
   	Bank	Connector	Terminal
   P0137	1	F79	110	Ground	Not existed
   P0157	2		98

3. Also check harness for short to power.

Is the inspection result normal?

YES

GO TO 5.

NO

Repair open circuit, short to ground or short to power in harness or connectors.

Refer to Component Inspection .

Is the inspection result normal?

YES

INSPECTION END

NO

Replace malfunctioning heated oxygen sensor 2. Refer to EXHAUST MANIFOLD AND THREE WAY CATALYST .