Definition of error code P0155
Fault in oxygen sensor O2 heating circuit (bank 2 sensor 1)
What does code P0155 mean?
When a P0155 code appears, it means that the oxygen sensor heating element is taking longer than usual to heat up. The Power Control Module (PCM) will register the P0155 trouble code and the Check Engine light will come on to alert the vehicle operator of the problem.
What causes the P0155 code?
- The oxygen sensor (bank 2 sensor 1) is not working properly.
- Damaged or bare wire leading to the oxygen sensor.
- A fuse in the oxygen sensor circuit has blown.
- The engine coolant temperature sensor does not work as it should
- The power control module (PCM) is defective (much less likely)
What are the symptoms of the P0155 code?
- Check Engine Light Turns On
- Vehicle malfunction
- Vehicle uses more fuel than usual
- Vehicle shuts down intermittently
- The exhaust smells like rotten eggs
- Black smoke is coming out of the exhaust pipe
- Some or all of these symptoms may occur with fault code P0155.
How does a mechanic diagnose a P0155 trouble code?
In most cases, the presence of this code means that the oxygen sensor needs to be replaced. Before doing so, perform the following steps:
- Use an OBD-II scanner to capture the trouble codes that have been stored by the power control module (PCM).
- Visually inspect the cables leading to the oxygen sensor for wire breaks or bare wires.
- Use an OBD-II scanner to view live data to make sure the oxygen sensor is working properly.
- If the coolant temperature sensor is not working properly, the power control module (PCM) will also register this code, so check and test it.
- In rare cases, the PCM may be defective, and this requires advanced diagnostics to determine if this is the problem. This should be treated last and only after all other repair attempts have failed.
Most common errors when diagnosing the P0155 code
- Replacing the oxygen sensor before checking other components.
- Failure to check the wires leading to the oxygen sensor for broken and/or stripped wires before replacing the oxygen sensor.
How serious is trouble code P0155?
Trouble code P0155 is considered a moderately serious code. The reason is that driving problems and poor fuel economy are possible when this trouble code is present.
What repairs can fix a P0155 code?
- Repair damaged or bare wires.
- Replace the coolant temperature sensor.
- Replace the oxygen sensor
- In rare cases, replace the power control module (PCM) when necessary.
Additional notes on code P0155
It may be difficult to remove the oxygen sensor if the oxygen sensor kit and propane tank are not available. The oxygen sensor may be difficult to access, depending on the vehicle. If the oxygen sensor has been seized in the exhaust, which is common, a heating element will be required to remove it.
