P0038
O2 Sensor Heater Control Circuit High (Bank 1 Sensor 2)
The engine computer has found a problem in the heater circuit for the oxygen sensor after the catalytic converter on bank 1. The circuit is drawing the wrong voltage, usually because of a short, wiring damage, or a failed sensor. This can keep the sensor from heating up correctly and can affect emissions control.
- SEV
- 3/5
- DRIVE
- CAUTION
- DIY
- $20–$200
- SHOP
- $120–$450
Quick answer
AI-CITATION READYWhat it means
Can you drive with it?
Most common causes
- Damaged or shorted wiring to the Bank 1 Sensor 2 oxygen sensor heater circuit
- Failed oxygen sensor heater element in Bank 1 Sensor 2
- Corroded, loose, or oil/heat-damaged connector at the downstream O2 sensor
Typical repair cost
DIY usually runs $20–$200. Typical shop repair lands around $120–$450, depending on the root cause.
01 / Definition
P0038 means the PCM/ECM detected a high voltage condition in the heater control circuit for HO2S Bank 1 Sensor 2, the downstream oxygen sensor located after the catalytic converter on bank 1. The heater circuit is monitored because the sensor needs to reach operating temperature quickly for accurate feedback. A high circuit reading usually points to a short to power, damaged wiring, corroded connector, blown fuse, or an internal sensor heater fault.
02 / Drive status
With caution. The vehicle is usually drivable, but the problem can increase emissions and may affect fuel control on some vehicles. Fix it soon, and do not ignore any rough running or additional warning lights.
03 / Symptoms
- Check Engine Light on
- Stored P0038 trouble code
- Possible increased fuel consumption
- Failed emissions test
- Possible delayed closed-loop operation after cold start
- Possible other oxygen sensor or heater codes
04 / Causes
| 1 | Damaged or shorted wiring to the Bank 1 Sensor 2 oxygen sensor heater circuit | high |
|---|---|---|
| 2 | Failed oxygen sensor heater element in Bank 1 Sensor 2 | high |
| 3 | Corroded, loose, or oil/heat-damaged connector at the downstream O2 sensor | medium |
| 4 | Blown fuse, relay fault, or power feed issue affecting the heater circuit | medium |
| 5 | PCM/ECM driver fault or control issue | low |
05 / Diagnostic sequence
- 01Confirm the code and check for related codes such as heater circuit, sensor voltage, or power supply faults.
- 02Inspect Bank 1 Sensor 2 wiring and connector for melted insulation, rubbing, corrosion, loose pins, or exhaust heat damage.
- 03Check the sensor heater fuse and related relay if equipped.
- 04Measure heater circuit resistance at the sensor and compare it to factory specifications.
- 05Verify power and ground supply to the heater circuit with a multimeter or test light.
- 06Check for battery voltage on the heater feed and look for a short to voltage on the control side.
- 07If wiring and power supply test good, replace the Bank 1 Sensor 2 oxygen sensor.
- 08Clear the code and road test to confirm the repair.
06 / Repairs
| 1 | Repair damaged wiring, terminals, or connector at Bank 1 Sensor 2 | $20–$150 |
|---|---|---|
| 2 | Replace blown fuse, faulty relay, or repair heater power feed | $10–$80 |
| 3 | Replace the Bank 1 Sensor 2 oxygen sensor | $50–$250 |
| 4 | Diagnose and repair PCM/ECM circuit driver problems if all other checks pass | $200–$800 |
07 / Related codes
08 / FAQ
What does Bank 1 Sensor 2 mean?
Bank 1 is the side of the engine with cylinder number 1. Sensor 2 is the oxygen sensor located after the catalytic converter on that bank.
Can a bad oxygen sensor cause P0038?
Yes. A failed heater element inside the downstream oxygen sensor is one of the most common causes.
Will clearing the code fix it?
No. The code will usually return if the wiring or sensor problem is still present.
Does P0038 mean the catalytic converter is bad?
Not usually. This code points to the oxygen sensor heater circuit, not the catalytic converter itself.
09 / Source and method
- DATA BASIS
- OBD-II REFERENCE + OBD2.HELP
- METHOD
- STATIC VALIDATION
- SAFETY
- INFORMATIONAL
This page combines OBD-II diagnostic reference data with OBD2.help generated diagnostic guidance for code meaning, likely causes, and repair direction.
Publishing uses deterministic schema and build validation, plus manual spot checks on representative pages before release.
Safety-critical diagnosis and repairs should be confirmed with a qualified mechanic, especially when the vehicle is misfiring, overheating, or losing power.