DTC P0037:00

HO2S heater control circuit low input

DETECTION CONDITION

The PCM monitors the HO2S heater output voltage. If the PCM turns the HO2S heater off but the HO2S heater circuit remains low voltage, the PCM determines that the HO2S heater circuit has a malfunction.

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 (Mode 2)/Snapshot data is available.
The DTC is stored in the PCM memory.

POSSIBLE CAUSE

HO2S connector or terminals malfunction
Short to ground or open circuit in HO2S heater power supply circuit
- Short to ground in wiring harness between ignition switch terminal A⁽¹⁾/relay block terminal 1B⁽²⁾ and HO2S terminal C
- ENG 20 A fuse malfunction
- Open circuit in wiring harness between ignition switch terminal A⁽¹⁾/relay block terminal 1B⁽²⁾ and HO2S terminal C
HO2S heater malfunction
Short to ground in wiring harness between HO2S terminal D and PCM terminal 2B
PCM connector or terminals malfunction
Open circuit in wiring harness between HO2S terminal D and PCM terminal 2B
PCM malfunction

⁽¹⁾	Vehicles without advanced keyless entry and push button start system

⁽²⁾	Vehicles with advanced keyless entry and push button start system

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 the repair order, then go to the next step.
2	VERIFY RELATED REPAIR INFORMATION AVAILABILITY Verify related Service Bulletins and/or on-line repair information availability. Is any related repair information available?	Yes	Perform repair or diagnosis according to the available repair information. If the vehicle is not repaired, go to the next step.
2		No	Go to the next step.
3	INSPECT HO2S CONNECTOR CONDITION Switch the ignition to off. Disconnect the HO2S connector. Inspect for poor connection (such as damaged/pulled-out pins, corrosion). Is there any malfunction?	Yes	Repair or replace the terminal and/or connector, then go to Step 9.
3		No	Go to the next step.
4	INSPECT HO2S HEATER POWER SUPPLY CIRCUIT FOR SHORT TO GROUND OR OPEN CIRCUIT HO2S connector is disconnected. Switch the ignition to ON (engine off). Measure the voltage between HO2S terminal C (wiring harness-side) and body ground. Is the voltage B+ ?	Yes	Go to the next step.
4		No	Inspect the ENG 20 A fuse. If the fuse is melted: Repair or replace the wiring harness for a possible short to ground. Replace the fuse. If the fuse is deteriorated: Replace the fuse. If the fuse is normal: Repair or replace the wiring harness for a possible open circuit. Go to Step 9.
5	INSPECT HO2S HEATER Switch the ignition to off. Inspect the HO2S heater. (See HEATED OXYGEN SENSOR (HO2S) INSPECTION ). Is there any malfunction?	Yes	Replace the HO2S, then go to Step 9. (See HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION ).
5		No	Go to the next step.
6	INSPECT HO2S HEATER CONTROL CIRCUIT FOR SHORT TO GROUND HO2S connector is disconnected. Inspect for continuity between HO2S terminal D (wiring harness-side) and body ground. Is there continuity?	Yes	Repair or replace the wiring harness for a possible short to ground, then go to Step 9.
6		No	Go to the next step.
7	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 terminal and/or connector, then go to Step 9.
7		No	Go to the next step.
8	INSPECT HO2S CONTROL CIRCUIT FOR OPEN CIRCUIT HO2S and PCM connectors are disconnected. Inspect for continuity between HO2S terminal D (wiring harness-side) and PCM terminal 2B (wiring harness-side). Is there continuity?	Yes	Go to the next step.
8		No	Repair or replace the wiring harness for a possible open circuit, then go to the next step.
9	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 ). Perform the KOEO or KOER self test. (See KOEO/KOER SELF TEST ).	Yes	Repeat the inspection from Step 1. If the malfunction recurs, replace the PCM. (See PCM REMOVAL/INSTALLATION ). Go to the next step.
9		No	Go to the next step.
10	VERIFY AFTER REPAIR PROCEDURE Perform the "AFTER REPAIR PROCEDURE". (See AFTER REPAIR PROCEDURE ). Are any DTCs present?	Yes	Go to the applicable DTC inspection. (See DTC TABLE ).
10		No	DTC troubleshooting completed.