OBD-II Error Code P0038: How to Fix It (HO2S Heater Control Circuit High Bank 1 Sensor 2)

Medium 30-60 minutes Medium Severity Verified June 2026
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Error Code
P0038
Brand
OBD-II Generic
Product Type
automotive
Severity
Medium
DIY Difficulty
Medium
Estimated Fix Time
30-60 minutes
Error code P0038 indicates a high voltage condition in the heater control circuit of the downstream oxygen sensor (Bank 1, Sensor 2). This usually points to a faulty oxygen sensor, wiring issue, or a problem with the sensor's heater circuit. While the vehicle may still be drivable, it can cause increased emissions and reduced fuel economy.
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Tools You'll Need

How to Fix Error Code P0038

  1. Read and Confirm the Code

  2. Visually Inspect the Oxygen Sensor and Wiring

    Ensure the engine is cool before working near the exhaust system.

  3. Test the Heater Circuit Voltage

    Be careful not to short circuit any wires. Disconnect the battery negative terminal when probing wires.

  4. Check the Heater Circuit Resistance

  5. Inspect the Fuse and Relay

    Always replace fuses with the correct amperage rating.

  6. Replace the Oxygen Sensor

    Use an oxygen sensor socket to avoid damaging the sensor. Apply anti-seize compound to the threads (if not pre-applied).

Parts You May Need

Oxygen sensor (Bank 1 Sensor 2)
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O2 sensor fuse
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Oxygen sensor (Bank 1 Sensor 2)
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O2 sensor fuse
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Oxygen sensor (Bank 1 Sensor 2)
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O2 sensor fuse
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Oxygen sensor (Bank 1 Sensor 2)
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O2 sensor fuse
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When to Call a Professional

If you are not comfortable working with electrical systems or if the problem persists after replacing the sensor, consult a professional mechanic. Additionally, if the code is accompanied by other codes or drivability issues, professional diagnosis may be needed.

Frequently Asked Questions

Can I drive with a P0038 code?
Yes, in most cases you can drive, but the vehicle may fail an emissions test and fuel economy may suffer. It's best to fix it promptly.
What happens if I ignore P0038?
Ignoring the code can lead to catalytic converter damage due to improper fuel mixture and increased emissions.
Where is Bank 1 Sensor 2 located?
Bank 1 refers to the side of the engine with cylinder #1. Sensor 2 is the downstream sensor, located after the catalytic converter on the exhaust pipe.
How much does it cost to fix P0038?
The cost typically ranges from $100 to $300 for DIY replacement of the oxygen sensor. Professional repair may cost $200-$500.
Will a bad oxygen sensor cause engine problems?
A bad downstream sensor (Sensor 2) usually does not affect engine performance directly, but it can cause the check engine light to come on and affect emissions.

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