Diagnosis Procedure

WARNING: This page is about a different car, the 2020 Infiniti QX60. However, it is still accessible from the selected car via links, so may be relevant.

CHECK A/F SENSOR 1 POWER SUPPLY CIRCUIT-I

Turn ignition switch OFF.
Disconnect A/F sensor 1 harness connector.
Turn ignition switch ON.

Check the voltage between A/F sensor 1 harness connector and ground.

DTC	+			-	Voltage
	A/F sensor 1
	Bank	Connector	Terminal
P0030	1	F72	1	Ground	Battery voltage
P0050	2	F73	1

Is the inspection result normal?

YES

GO TO 2.

GO TO 4.

CHECK A/F SENSOR 1 HEATER OUTPUT SIGNAL CIRCUIT

Turn ignition switch OFF.
Disconnect ECM harness connector.

Check the continuity between A/F sensor 1 harness connector and ECM harness connector.

DTC	A/F sensor 1			ECM		Continuity
DTC	Bank	Connector	Terminal	Connector	Terminal	Continuity
P0030	1	F72	2	F79	94	Existed
P0050	2	F73	2	F79	151	Existed

Also check harness for short to power and short to ground.

Is the inspection result normal?

YES

GO TO 3.

Repair or replace error-detected parts.

CHECK A/F SENSOR 1 HEATER
Check A/F sensor 1 heater. Refer to Component Inspection (A/F Sensor 1 Heater) .

Is the inspection result normal?

YES

INSPECTION END

NO

Replace malfunctioning A/F sensor 1. Refer to EXHAUST MANIFOLD AND THREE WAY CATALYST .

CHECK A/F SENSOR 1 POWER SUPPLY CIRCUIT-II

Turn ignition switch OFF.
Disconnect IPDM E/R harness connector.

Check the continuity between IPDM E/R harness connector and A/F sensor 1 harness connector.

DTC	IPDM E/R		A/F sensor 1		Continuity
	Connector	Terminal	Connector	Terminal
P0030	F19	53	F72	1	Existed
P0050			F73	1

Also check harness for short to ground.

Is the inspection result normal?

YES

Perform the trouble diagnosis for power supply circuit.

Repair or replace error-detected parts.