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.

Loosen and retighten the A/F sensor 1. Refer to EXHAUST MANIFOLD AND THREE WAY CATALYST .

GO TO 3.

1. Start engine and run it at idle.
2. Listen for an exhaust gas leak before three way catalyst 1.

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Is exhaust gas leak detected?

YES

Repair or replace.

NO

GO TO 4.

Listen for an intake air leak after the mass air flow sensor.

Is intake air leak detected?

YES

Repair or replace.

NO

GO TO 5.

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, P0172, P0174 or P0175 detected? Is it difficult to start engine?

YES

Perform trouble diagnosis for DTC P0171, P0174 or P0172, P0175. Refer to DTC Description  or DTC Description .

NO

GO TO 6.

1. Disconnect A/F sensor 1 harness connector.
2. Turn ignition switch ON.
3. Check the voltage between A/F sensor 1 harness connector and ground.

   DTC	+			-	Voltage
   	A/F sensor 1
   	Bank	Connector	Terminal
   P014C P014D P015A P015B	1	F72	1	Ground	Battery voltage
   P014E P014F P015C P015D	2	F73	1

Is the inspection result normal?

YES

GO TO 8.

NO

GO TO 7.

Check the following.

• IPDM E/R harness connector F19
• 15A fuse (No. 40)
• Harness for open or short between A/F sensor 1 and fuse

Repair or replace harness or connectors.

1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Check the continuity between A/F sensor 1 harness connector and ECM harness connector.

   DTC	A/F sensor 1			ECM		Continuity
   	Bank	Connector	Terminal	Connector	Terminal
   P014C P014D P015A P015B	1	F72	3	F79	102	Existed
   			4		101
   P014E P014F P015C P015D	2	F73	3		111
   			4		107

4. Check the continuity between A/F sensor 1 harness connector and ground, or ECM harness connector and ground.

   DTC	A/F sensor 1			--	Continuity
   	Bank	Connector	Terminal
   P014C P014D P015A P015B	1	F72	3	Ground	Not existed
   			4
   P014E P014F P015C P015D	2	F73	3
   			4

   DTC	ECM			--	Continuity
   	Bank	Connector	Terminal
   P014C P014D P015A P015B	1	F79	102	Ground	Not existed
   			101
   P014E P014F P015C P015D	2		111
   			107

5. Also check harness for short to power.

Is the inspection result normal?

YES

GO TO 9.

NO

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

Refer to Component Inspection (A/F Sensor 1 Heater) .

Is the inspection result normal?

YES

GO TO 10.

NO

Replace malfunctioning air fuel ratio (A/F) sensor 1. Refer to EXHAUST MANIFOLD AND THREE WAY CATALYST .

Check both mass air flow sensor.

Refer to Component Inspection (Mass Air Flow Sensor) .

Is the inspection result normal?

YES

GO TO 11.

NO

Replace malfunctioning mass air flow sensor. Refer to INTAKE MANIFOLD COLLECTOR .

Refer to Inspection .

Is the inspection result normal?

YES

Replace malfunctioning air fuel ratio (A/F) sensor 1. Refer to EXHAUST MANIFOLD AND THREE WAY CATALYST .

NO

Repair or replace PCV valve. Refer to Component Parts Location .