DTC P0037 [L3]

BME010200001W03

DTC P0037

Rear HO2S heater circuit low input

DETECTION CONDITION

• PCM monitors rear HO2S heater control signal at PCM terminal 4D. If PCM turns rear HO2S heater off but rear HO2S heater circuit has low voltage, PCM determines that rear HO2S heater circuit has malfunction.
Diagnostic support note
• This is an intermittent monitor (O2 sensor heater).
• MIL illuminates if PCM detects the above malfunction condition in two consecutive drive cycles or in one drive cycle while DTC for the same malfunction has been stored in PCM.
• PENDING CODE is available if PCM detects the above malfunction condition.
• FREEZE FRAME DATA is available.
• DTC is stored in PCM memory.

POSSIBLE CAUSE

• Rear HO2S malfunction
• Open circuit between the ignition switch and rear HO2S terminal C
• Open circuit between the rear HO2S terminal D and PCM terminal 4D
• Short to ground circuit between rear HO2S terminal D and PCM terminal 4D
• Poor connection at rear HO2S or PCM connector
• PCM malfunction

Diagnostic procedure

STEP

INSPECTION

ACTION

1
PERFORM DTC CONFIRMATION PROCEDURE
• Perform DTC CONFIRMATION PROCEDURE.
• Is same DTC present?
Yes
Go to next step.
No
Intermittent concern exists. Go to INTERMITTENT CONCERN TROUBLESHOOTING procedure.
2
INSPECT POOR CONNECTION OF REAR HO2S CONNECTOR
• Turn ignition key to OFF.
• Disconnect rear HO2S connector.
• Inspect for poor connection (damaged, pulled-out pins, corrosion, etc.).
• Is there any malfunction?
Yes
Repair or replace terminal, then go to Step 8.
No
Go to next step.
3
INSPECT REAR HO2S HEATER
• Inspect rear HO2S heater.
• Is rear HO2S heater okay?
Yes
Go to next step.
No
Replace rear HO2S, then go to Step 8.
4
INSPECT REAR HO2S HEATER POWER CIRCUIT FOR OPEN CIRCUIT
• Turn ignition key to ON (Engine OFF).
• Measure voltage between rear HO2S terminal C (harness-side) and body ground.
• Is voltage B+?
Yes
Go to next step.
No
Repair or replace harness for open circuit, then go to Step 8.
5
INSPECT POOR CONNECTION OF PCM CONNECTOR
• Turn ignition key to OFF.
• Disconnect PCM connector.
• Inspect for poor connection (damaged, pulled-out pins, corrosion, etc.).
• Is there any malfunction?
Yes
Repair terminal, then go to Step 8.
No
Go to next step.
6
INSPECT REAR HO2S HEATER CONTROL CIRCUIT FOR SHORT TO GROUND
• Inspect continuity between rear HO2S terminal D (harness-side) and body ground.
• Is there continuity?
Yes
Repair or replace harness for short to ground, then go to Step 8.
No
Go to next step.
7
INSPECT HREAR HO2S HEATER CONTROL CIRCUIT FOR OPEN CIRCUIT
• Inspect continuity between rear HO2S terminal D (harness-side) and PCM terminal 4D.
• Is there continuity?
Yes
Go to next step.
No
Repair or replace harness for open circuit, then go to Step 8.
8
VERIFY TROUBLESHOOTING OF DTC P0037 COMPLETED
• Make sure to reconnect all disconnected connectors.
• Clear DTC from PCM memory using WDS or equivalent.
• Perform KOEO/KOER self-test.
• Is same DTC present?
Yes
Replace PCM, then go to next step.
No
Go to next step.
9
VERIFY AFTER REPAIR PROCEDURE
• Perform "After Repair Procedure".
• Is there any DTC present?
Yes
Go to applicable DTC troubleshooting.
No
Troubleshooting completed.