Home

Mazdamanuals.com

 DTC P0031 [L3 Turbo]

DTC P0031 [L3 Turbo]

id0102b7802000

DTC P0031

A/F sensor heater circuit low input

DETECTION CONDITION

• The PCM monitors the A/F sensor heater output voltage. If the PCM turns the A/F sensor heater off or on but the A/F sensor heater circuit voltage remains low the PCM determines that the A/F sensor heater circuit has a malfunction.
Note
• The A/F sensor heater is controlled by a duty signal.
Diagnostic support note
• This is a continuous monitor (A/F sensor heater, 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.
• PENDING CODE is available if the PCM detects the above malfunction condition during the first drive cycle.
• FREEZE FRAME DATA is available.
• DTCs are stored in the PCM memory.

POSSIBLE CAUSE

• A/F sensor heater malfunction
• Connector or terminal malfunction
• Open circuit in the wiring harness between main relay and A/F sensor terminal 2B
• Short to ground in the wiring harness between main relay and A/F sensor terminal 2B
• Open circuit in the wiring harness between A/F sensor terminal 2D and PCM terminal 4AD
• Short to ground in the wiring harness between A/F sensor terminal 2D and PCM terminal 4AD
• PCM malfunction

Diagnostic procedure

STEP

INSPECTION

ACTION

1
VERIFY FREEZE FRAME DATA AND DIAGNOSTIC MONITORING TEST RESULTS 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 the next step.
2
VERIFY RELATED REPAIR 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 the next step.
No
Go to the next step.
3
INSPECT A/F SENSOR CONNECTOR FOR POOR CONNECTION
• Turn the ignition switch off.
• Disconnect the A/F sensor connector.
• Inspect for poor connection (such as damaged/pulled-out pins, and corrosion).
• Is there any malfunction?
Yes
Repair or replace the terminal, then go to Step 7.
No
Go to the next step.
4
INSPECT A/F SENSOR HEATER CONTROL CIRCUIT FOR SHORT TO POWER SUPPLY
• Turn the ignition switch to the ON position (Engine off).
• Measure the voltage between A/F sensor terminal 2D (wiring harness-side) and body ground.
• Is the voltage B+?
Yes
Repair or replace the wiring harness for a possible short to power supply, then go to Step 7.
No
Go to the next step.
5
INSPECT A/F SENSOR HEATER
• Inspect the A/F sensor heater.
• Is there any malfunction?
Yes
Replace the A/F sensor, then go to Step 7.
No
Go to the next step.
6
INSPECT PCM CONNECTOR FOR POOR CONNECTION
• Turn the ignition switch off.
• Disconnect the PCM connector.
• Inspect for poor connection (such as damaged/pulled-out pins, and corrosion).
• Is there any malfunction?
Yes
Repair or replace the terminal, then go to the next step.
No
Go to the next step.
7
VERIFY TROUBLESHOOTING OF DTC P0031 COMPLETED
• Make sure to reconnect all disconnected connectors.
• Clear the DTC from the PCM memory using the WDS or equivalent.
• Perform the A/F sensor heater, HO2S heater, A/F sensor, HO2S, and TWC Repair Verification Drive Mode.
• Is the PENDING CODE for this DTC present?
Yes
Replace the PCM, then go to the next step.
No
Go to the next step.
8
VERIFY AFTER REPAIR PROCEDURE
• Perform the "AFTER REPAIR PROCEDURE".
• Are any DTCs present?
Yes
Go to the applicable DTC inspection.
No
DTC troubleshooting completed.