DTC P0161[AJ (3.0L Duratec)]

DTC P0161	Rear HO2S (LH) heater circuit malfunction
DETECTION CONDITION	• The PCM checks rear HO2S (LH) heater circuit for open/shorts and excessive current draw. If the current draw exceeds a calibrated limit and/or open or short is detected, the PCM determines the rear HO2S (LH) heater circuit is malfunction.
POSSIBLE CAUSE	• Short to power supply circuit in harness or rear HO2S (LH) heater • Water in harness connector • Open circuit in wiring between rear HO2S (LH) terminal C and main relay terminal B • Open circuit in wiring between rear HO2S (LH) terminal A and PCM terminal 96 • Low battery voltage • Corrosion or poor mating terminals and wiring • Damaged rear HO2S (LH) heater • Damaged PCM

DTC P0161

Rear HO2S (LH) heater circuit malfunction

DETECTION CONDITION

• The PCM checks rear HO2S (LH) heater circuit for open/shorts and excessive current draw. If the current draw exceeds a calibrated limit and/or open or short is detected, the PCM determines the rear HO2S (LH) heater circuit is malfunction.

POSSIBLE CAUSE

• Short to power supply circuit in harness or rear HO2S (LH) heater

• Water in harness connector

• Open circuit in wiring between rear HO2S (LH) terminal C and main relay terminal B

• Open circuit in wiring between rear HO2S (LH) terminal A and PCM terminal 96

• Low battery voltage

• Corrosion or poor mating terminals and wiring

• Damaged rear HO2S (LH) heater

• Damaged PCM

STEP	INSPECTION	ACTION
1	VERIFY FREEZE FRAME DATA HAS BEEN RECORDED • Has FREEZE FRAME DATA been recorded?	Yes	Go to the next step.
No	Record the FREEZE FRAME DATA on the repair order, then go to next step.
2	VERIFY SERVICE INFORMATION AVAILABILITY • Verify related Service Information availability. • Is any related Service Information available?	Yes	Perform repair or diagnosis according to the available Service Information. • If the vehicle is not repaired, go to next step.
No	Go to next step.
3	INDETIFY TRIGGER DTC FOR FEEZE FRAME DATA • Is DTC P0161 on FREEZE FRAME DATA?	Yes	Go to the next step.
No	Go to FREEZE FRAME DATA DTC inspection. (See DTC TABLE[AJ (3.0L Duratec)].)
4	CHECK FOR REAR HO2S (LH) HARNESS CONNECTOR Note • Refer to the PCM connector pin number in the beginning of this pinpoint test. • Visually inspect the rear HO2S (LH) circuit for exposed wiring, water contamination, corrosion and proper assembly. • Were any concerns found during inspection?	Yes	Repair any concerns found during inspection, then go to Step 11.
No	Go to the next step.
5	PERFORM KEY ON ENGINE OFF (KOEO) SELF TEST • Connect the M-MDS to DLC-2. • Turn the ignition switch to the ON position. • Perform KOEO self test. • Is DTCs P0135, P0141, P0155 or P0161 present?	Yes	Go to the next step.
No	Intermittent malfunction exist, go to the Step 11.
6	CHECK VPWR VOLTAGE TO REAR HO2S (LH) HARNESS VONNECTOR Note • If DTCs P0161 and P0135 or P0141 and P0155 are displayed, both heater circuits will require testing. DTCs displayed separately are to be test individually. • Disconnect rear HO2S (LH) connector. • Turn the ignition switch to the ON position. • Measure voltage between terminal C and D at rear HO2S (LH) harness side connector. • Is the voltage greater than 10.5 V?	Yes	Go to the next step.
No	Inspect fuse in VPWR circuit. If fuse is normal repair open circuit. Then go to Step 11.
7	CHECK REAR HO2S (LH) HEATER CIRCUIT FOR SHORT TO VPWR AND GROUND • Disconnect PCM. • Measure resistance between following PCM harness side connector terminals: ― Between terminal 96 and 24, 51, 76, 103 ― Between terminal 96 and 91 ― Between terminal 96 and 71, 97 • Is each resistance greater than 10,000 ohms?	Yes	Go to the next step.
No	Repair short to VPWR or ground circuit, then go to Step 11.
8	CHECK REAR HO2S (LH) HEATER CIRCUIT FOR OPEN IN HARNESS • Measure resistance at harness side connectors between rear HO2S (LH) terminal A and PCM terminal 96 • Is the resistance less than 5.0 ohms?	Yes	Go to the next step.
No	Repair for open or excessive resistance in the rear HO2S (LH) heater circuit in harness, then go to Step 11.
9	CHECK REAR HO2S (LH) HEATER RESISITANCE • Measure resistance at rear HO2S (LH) component side connector between C and A. • Is resistance 2—50 ohms?	Yes	Go to the next step.
No	Replace rear HO2S (LH), then go to Step 11.
10	CHECK REAR HO2S (LH) CASE FOR SHORT TO VPWR, HEATER CONTROL AND SIGNAL RETURN • Measure resistance for following: • Between rear HO2S (LH) component side connector terminal A and rear HO2S (LH) case • Between terminal A and D at rear HO2S (LH) component side connector. • Between rear HO2S (LH) component side connector terminal C and rear HO2S (LH) case • Is the resistance greater than 10,000 ohms?	Yes	Replace PCM, then go to the next step.
No	Replace rear HO2S (LH), then go to the next step.
11	VERIFY TROUBLESHOOTING OF DTC P0161 COMPLETED • Make sure to reconnect all disconnected connectors. • Clear the DTC from the PCM memory using the M-MDS. • Perform KOEO/KOER self test. (See KOEO/KOER SELF TEST[AJ (3.0L Duratec)].) • Is the PENDING CODE same DTC present?	Yes	Replace PCM, then go to next step. (See PCM REMOVAL/INSTALLATION[AJ (3.0L Duratec)].)
No	Go to next step.
12	VERIFY AFTER REPAIR PROCEDURE • Perform "AFTER REPAIR PROCEDURE". (See AFTER REPAIR PROCEDURE[AJ (3.0L Duratec)].) • Is there any DTC present?	Yes	Go to applicable DTC inspection. (See DTC TABLE[AJ (3.0L Duratec)].)
No	Troubleshooting completed.

STEP

INSPECTION

ACTION

VERIFY FREEZE FRAME DATA HAS BEEN RECORDED

• Has FREEZE FRAME DATA been recorded?

Yes

Go to the next step.

Record the FREEZE FRAME DATA on the repair order, then go to next step.

VERIFY SERVICE INFORMATION AVAILABILITY

• Verify related Service Information availability.

• Is any related Service Information available?

Yes

Perform repair or diagnosis according to the available Service Information.

• If the vehicle is not repaired, go to next step.

Go to next step.

INDETIFY TRIGGER DTC FOR FEEZE FRAME DATA

• Is DTC P0161 on FREEZE FRAME DATA?

Yes

Go to the next step.

Go to FREEZE FRAME DATA DTC inspection.

(See DTC TABLE[AJ (3.0L Duratec)].)

CHECK FOR REAR HO2S (LH) HARNESS CONNECTOR

Note

• Refer to the PCM connector pin number in the beginning of this pinpoint test.

• Visually inspect the rear HO2S (LH) circuit for exposed wiring, water contamination, corrosion and proper assembly.

• Were any concerns found during inspection?

Yes

Repair any concerns found during inspection, then go to Step 11.

Go to the next step.

PERFORM KEY ON ENGINE OFF (KOEO) SELF TEST

• Connect the M-MDS to DLC-2.

• Turn the ignition switch to the ON position.

• Perform KOEO self test.

• Is DTCs P0135, P0141, P0155 or P0161 present?

Yes

Go to the next step.

Intermittent malfunction exist, go to the Step 11.

CHECK VPWR VOLTAGE TO REAR HO2S (LH) HARNESS VONNECTOR

Note

• If DTCs P0161 and P0135 or P0141 and P0155 are displayed, both heater circuits will require testing. DTCs displayed separately are to be test individually.

• Disconnect rear HO2S (LH) connector.

• Turn the ignition switch to the ON position.

• Measure voltage between terminal C and D at rear HO2S (LH) harness side connector.

• Is the voltage greater than 10.5 V?

Yes

Go to the next step.

Inspect fuse in VPWR circuit.

If fuse is normal repair open circuit.

Then go to Step 11.

CHECK REAR HO2S (LH) HEATER CIRCUIT FOR SHORT TO VPWR AND GROUND

• Disconnect PCM.

• Measure resistance between following PCM harness side connector terminals:

― Between terminal 96 and 24, 51, 76, 103

― Between terminal 96

and 91

― Between terminal 96 and 71, 97

• Is each resistance greater than 10,000 ohms?

Yes

Go to the next step.

Repair short to VPWR or ground circuit, then go to Step 11.

CHECK REAR HO2S (LH) HEATER CIRCUIT FOR OPEN IN HARNESS

• Measure resistance at harness side connectors between rear HO2S (LH) terminal A and PCM terminal 96

• Is the resistance less than 5.0 ohms?

Yes

Go to the next step.

Repair for open or excessive resistance in the rear HO2S (LH) heater circuit in harness, then go to Step 11.

CHECK REAR HO2S (LH) HEATER RESISITANCE

• Measure resistance at rear HO2S (LH) component side connector between C and A.

• Is resistance 2—50 ohms?

Yes

Go to the next step.

Replace rear HO2S (LH), then go to Step 11.

CHECK REAR HO2S (LH) CASE FOR SHORT TO VPWR, HEATER CONTROL AND SIGNAL RETURN

• Measure resistance for following:

• Between rear HO2S (LH) component side connector terminal A and rear HO2S (LH) case

• Between terminal A and D at rear HO2S (LH) component side connector.

• Between rear HO2S (LH) component side connector terminal C and rear HO2S (LH) case

• Is the resistance greater than 10,000 ohms?

Yes

Replace PCM, then go to the next step.

Replace rear HO2S (LH), then go to the next step.

VERIFY TROUBLESHOOTING OF DTC P0161 COMPLETED

• Make sure to reconnect all disconnected connectors.

• Clear the DTC from the PCM memory using the M-MDS.

• Perform KOEO/KOER self test.

(See KOEO/KOER SELF TEST[AJ (3.0L Duratec)].)

• Is the PENDING CODE same DTC present?

Yes

Replace PCM, then go to next step.

(See PCM REMOVAL/INSTALLATION[AJ (3.0L Duratec)].)

Go to next step.

VERIFY AFTER REPAIR PROCEDURE

• Perform "AFTER REPAIR PROCEDURE".

(See AFTER REPAIR PROCEDURE[AJ (3.0L Duratec)].)

• Is there any DTC present?

Yes

Go to applicable DTC inspection.

(See DTC TABLE[AJ (3.0L Duratec)].)

Troubleshooting completed.