OBD-II Generic Error Code P0155: How to Fix It

Medium 1-2 hours Medium Severity Verified June 2026
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Error Code
P0155
Brand
OBD-II Generic
Product Type
automotive
Severity
Medium
DIY Difficulty
Medium
Estimated Fix Time
1-2 hours
Error code P0155 indicates a problem with the heater circuit in the oxygen sensor located on Bank 2, Sensor 1 (upstream of the catalytic converter). This means the engine control module (ECM) has detected a malfunction in the sensor's heating element, which can cause poor fuel economy and increased emissions. The fix typically involves checking the sensor's wiring, fuse, and replacing the sensor if needed.
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Tools You'll Need

How to Fix Error Code P0155

  1. Safety Precautions

    Always work on a cool engine to avoid burns. Disconnect the battery to prevent electrical shock or damage.

  2. Locate the O2 Sensor

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  3. Inspect Wiring and Connector

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  4. Check the Heater Circuit Fuse

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  5. Test the O2 Sensor Heater Circuit

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  6. Replace the O2 Sensor (If Faulty)

    Be careful not to overtighten, as this can damage the threads.

  7. Clear the Code and Test Drive

    If the code returns, there may be an underlying wiring issue or ECM problem requiring professional diagnosis.

Parts You May Need

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

If replacing the sensor does not clear the code, or if you suspect a wiring issue beyond the sensor connector, a professional mechanic should diagnose the circuit to avoid damaging the ECM.

Frequently Asked Questions

Can I drive with a P0155 code?
You can drive short distances, but it may cause poor fuel economy and increased emissions. Prolonged driving can damage the catalytic converter.
How much does it cost to fix P0155?
DIY cost is around $50-$150 for the sensor and tools. Professional repair can cost $200-$400 including labor.
What does Bank 2 Sensor 1 mean?
Bank 2 is the side of the engine opposite cylinder #1. Sensor 1 is the upstream sensor before the catalytic converter.
Can a bad fuse cause P0155?
Yes, a blown heater circuit fuse can trigger P0155. Check the fuse before replacing the sensor.
What tools do I need to replace the O2 sensor?
You'll need an O2 sensor socket, wrench, multimeter, and OBD2 scanner. Anti-seize compound is recommended.

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