DTC P0031:00 [MZR 1.6]

id0102h3700400

DTC P0031:00

A/F sensor heater control circuit low input
DETECTION CONDITION
•  If the input voltage to the A/F sensor heater drive terminal in the PCM is low for 1 s or more even though the A/F sensor is duty-controlled at under 90% by the PCM.
Note
•  A/F sensor heater is controlled by duty signal.
Diagnostic support note
•  This is an intermittent monitor (A/F sensor heater, HO2S heater).
•  The check engine light 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 (Mode 2)/Snapshot data is available.
•  DTC is stored in the PCM memory.
POSSIBLE CAUSE
•  A/F sensor connector or terminals malfunction
•  A/F sensor heater malfunction
•  PCM connector or terminals malfunction
•  Short to ground in wiring harness between the following terminals:
―  A/F sensor terminal C—PCM terminal 2C
―  A/F sensor terminal D—PCM terminal 2BD
•  Open circuit in wiring harness between the following terminals:
―  A/F sensor terminal C—PCM terminal 2C
―  A/F sensor terminal D—PCM terminal 2BD
•  PCM malfunction

Diagnostic Procedure

STEP

INSPECTION

ACTION
1
VERIFY FREEZE FRAME DATA (MODE 2)/SNAPSHOT DATA AND DIAGNOSTIC MONITORING TEST RESULTS HAVE BEEN RECORDED
•  Have the FREEZE FRAME DATA (Mode 2)/snapshot data and DIAGNOSTIC MONITORING TEST RESULTS (A/F sensor heater, HO2S heater related) been recorded?
Yes
Go to the next step.
No
Record the FREEZE FRAME DATA (Mode 2)/snapshot data and DIAGNOSTIC MONITORING TEST RESULTS on repair order, then go to the next step.
2
VERIFY RELATED 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 the next step.
No
Go to the next step.
3
INSPECT A/F SENSOR CONNECTOR CONDITION
•  Switch the ignition off.
•  Disconnect the A/F sensor connector.
•  Inspect for poor connection (such as damaged/pulled-out pins, corrosion).
•  Is there any malfunction?
Yes
Repair or replace the connector or terminals, then go to Step 8.
No
Go to the next step.
4
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 8.
(See AIR FUEL RATIO (A/F) SENSOR REMOVAL/INSTALLATION [MZR 1.6].)
No
Go to the next step.
5
INSPECT PCM CONNECTOR CONDITION
•  Disconnect the PCM connector.
•  Inspect for poor connection (such as damaged/pulled-out pins, corrosion).
•  Is there any malfunction?
Yes
Repair or replace the connector or terminals, then go to Step 8.
No
Go to the next step.
6
INSPECT A/F SENSOR HEATER CIRCUIT FOR SHORT TO GROUND
•  Verify that the A/F sensor and PCM connectors are disconnected.
•  Inspect for continuity between the following terminals (wiring harness-side) and body ground:
―  A/F sensor terminal C
―  A/F sensor terminal D
•  Is there continuity?
Yes
Refer to the wiring diagram and verify whether or not there is a common connector between the following terminals:
•  A/F sensor terminal C—PCM terminal 2C
•  A/F sensor terminal D—PCM terminal 2BD
If there is a common connector:
•  Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness for a short to ground.
•  Repair or replace the malfunctioning part.
If there is no common connector:
•  Repair or replace the wiring harness which has a short to ground.
Go to Step 8.
No
Go to the next step.
7
INSPECT A/F SENSOR HEATER CIRCUIT FOR OPEN CIRCUIT
•  Verify that the A/F sensor and PCM connectors are disconnected.
•  Inspect for continuity between the following terminals (wiring harness-side):
―  A/F sensor terminal C—PCM terminal 2C
―  A/F sensor terminal D—PCM terminal 2BD
•  Is there continuity?
Yes
Go to the next step.
No
Refer to the wiring diagram and verify whether or not there is a common connector between the following terminals:
•  A/F sensor terminal C—PCM terminal 2C
•  A/F sensor terminal D—PCM terminal 2BD
If there is a common connector:
•  Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness for an open circuit.
•  Repair or replace the malfunctioning part.
If there is no common connector:
•  Repair or replace the wiring harness which has an open circuit.
Go to the next step.
8
VERIFY DTC TROUBLESHOOTING COMPLETED
•  Always reconnect all disconnected connectors.
•  Clear the DTC from the PCM memory using the M-MDS.
•  Perform the KOEO or KOER self test.
•  Is the PENDING CODE for this DTC present?
Yes
Repeat the inspection from Step 1.
•  If the malfunction recurs, replace the PCM.
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 inspection.
(See DTC TABLE [MZR 1.6].)
No
DTC troubleshooting completed.