DTC P0031:00 [MZR 1.5, MZR 1.6]

id0102f0700400

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 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 function 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.

•  The DTC is stored in the PCM memory.

POSSIBLE CAUSE

•  A/F sensor connector or terminals malfunction

•  A/F sensor heater malfunction

•  Short to ground in wiring harness between the following terminals:

―  A/F sensor terminal C—PCM terminal 2I

―  A/F sensor terminal D—PCM terminal 2X

•  PCM connector or terminals malfunction

•  Open circuit in wiring harness between the following terminals:

―  A/F sensor terminal C—PCM terminal 2I

―  A/F sensor terminal D—PCM terminal 2X

•  PCM malfunction

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 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 function 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. • The DTC is stored in the PCM memory.
POSSIBLE CAUSE	• A/F sensor connector or terminals malfunction • A/F sensor heater malfunction • Short to ground in wiring harness between the following terminals: ― A/F sensor terminal C—PCM terminal 2I ― A/F sensor terminal D—PCM terminal 2X • PCM connector or terminals malfunction • Open circuit in wiring harness between the following terminals: ― A/F sensor terminal C—PCM terminal 2I ― A/F sensor terminal D—PCM terminal 2X • 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.
1		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.
2		No	Go to the next step.
3	INSPECT A/F SENSOR CONNECTOR AND TERMINALS • Switch the ignition to 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 connector or terminals, then go to Step 8.
3		No	Go to the next step.
4	INSPECT A/F SENSOR HEATER • Inspect the A/F sensor heater. (See AIR FUEL RATIO (A/F) SENSOR INSPECTION [MZR 1.5, MZR 1.6].) • 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 1.5, MZR 1.6].)
4		No	Go to the next step.
5	INSPECT A/F SENSOR HEATER CIRCUIT FOR SHORT TO GROUND • A/F sensor connector is 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	If the short to ground circuit could be detected: • Repair or replace the wiring harness for a possible short to ground. If the short to ground circuit could not be detected: • Replace the PCM (short to ground in PCM internal circuit). (See PCM REMOVAL/INSTALLATION [MZR 1.5, MZR 1.6].) Go to Step 8.
5		No	Go to the next step.
6	INSPECT PCM CONNECTOR AND TERMINALS • 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 connector or terminals, then go to Step 8.
6		No	Go to the next step.
7	INSPECT A/F SENSOR HEATER CIRCUIT FOR OPEN CIRCUIT • 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 2I ― A/F sensor terminal D—PCM terminal 2X • Is there continuity?	Yes	Go to the next step.
7		No	Repair or replace the wiring harness for a possible open circuit, then go to the next step.
8	VERIFY DTC TROUBLESHOOTING COMPLETED • Make sure to reconnect all disconnected connectors. • Clear the DTC from the PCM memory using the M-MDS. (See AFTER REPAIR PROCEDURE [MZR 1.5, MZR 1.6].) • Perform the KOEO or KOER self test. (See KOEO/KOER SELF TEST [MZR 1.5, MZR 1.6].) • Is the PENDING CODE for this DTC present?	Yes	Repeat the inspection from Step 1. • If the malfunction recurs, replace the PCM. (See PCM REMOVAL/INSTALLATION [MZR 1.5, MZR 1.6].) Go to the next step.
8		No	Go to the next step.
9	VERIFY AFTER REPAIR PROCEDURE • Perform the “AFTER REPAIR PROCEDURE”. (See AFTER REPAIR PROCEDURE [MZR 1.5, MZR 1.6].) • Are any DTCs present?	Yes	Go to the applicable DTC inspection. (See DTC TABLE [MZR 1.5, MZR 1.6].)
9		No	DTC troubleshooting completed.