P0038 Code – HO2S Heater Control Circuit High (Bank 1 Sensor 2)
P0038 is an OBD-II diagnostic trouble code that indicates the Engine Control Module (ECM) has detected a high voltage condition in the heater control circuit of the downstream heated oxygen sensor (Bank 1 Sensor 2).
Code Meaning
P0038 – HO2S Heater Control Circuit High (Bank 1 Sensor 2)
Symptoms
- Check Engine Light is ON.
- Increased fuel consumption.
- Higher exhaust emissions.
- Delayed oxygen sensor warm-up.
- Usually no major drivability problems.
Possible Causes
- Faulty Bank 1 Sensor 2 oxygen sensor heater.
- Short to battery voltage in the heater circuit.
- Damaged or melted wiring harness.
- Corroded or loose electrical connector.
- Faulty ECM (rare).
Sensor Location
Bank 1 Sensor 2 is the oxygen sensor located after the catalytic converter on the engine bank containing cylinder number 1.
How to Diagnose
- Scan and confirm DTC P0038.
- Inspect the sensor connector and wiring for damage.
- Check for excessive voltage in the heater circuit.
- Measure heater resistance with a digital multimeter.
- Verify proper power and ground supply.
- Replace the oxygen sensor if the heater element has failed.
Common Repairs
- Replace the downstream oxygen sensor.
- Repair shorted or damaged wiring.
- Clean or replace faulty connectors.
- Repair the heater control circuit.
- Replace the ECM only after confirming all other components are good.
Can You Drive with P0038?
Yes. The vehicle is generally safe to drive, but fuel economy and emissions may be negatively affected. Repairing the problem promptly is recommended.
Related OBD-II Codes
- P0036 – HO2S Heater Control Circuit (Bank 1 Sensor 2)
- P0037 – HO2S Heater Control Circuit Low (Bank 1 Sensor 2)
- P0136 – O2 Sensor Circuit Malfunction (Bank 1 Sensor 2)
- P0141 – O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 2)