DTC P0037 [LF, L3]

id0102008022a3

DTC P0037

Rear HO2S heater circuit low input

DETECTION CONDITION

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

POSSIBLE CAUSE

• Rear HO2S malfunction
• Open circuit between ignition switch and rear HO2S terminal C
• Open circuit between 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 the PCM connector
• PCM malfunction

Diagnostic procedure

STEP

INSPECTION

ACTION

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