P0155 Technical Description
Oxygen O2 Sensor Heater Circuit Malfunction (Bank 2, Sensor 1)
If you’re seeing the P0155 trouble code, this guide will explain its meaning, symptoms, causes, and fixes.
I’ve tackled this issue many times in my years as a mechanic.
We’ll dive into what P0155 indicates, how it affects your car, and the steps to fix it.
Let’s get started.
Key Takeaways
- P0155 indicates a malfunction in the heater circuit of the O2 sensor on Bank 2, Sensor 1.
- Common symptoms include the check engine light, poor fuel economy, and rough idling.
- Causes range from a faulty O2 sensor to damaged wiring or a blown fuse.
- Diagnosing involves scanning the vehicle, inspecting the sensor, and testing the heater circuit.
- Replacing the O2 sensor or fixing wiring issues are common solutions.
- Clearing the code and test-driving confirms the repair is successful.
Table of ContentsShow
What Does P0155 Trouble Code Mean?
The P0155 trouble code indicates that there is an issue with the heater circuit in the oxygen sensor (O2 sensor) located on Bank 2, Sensor 1 of your vehicle.
The O2 sensor measures the amount of oxygen in the exhaust gases as they leave the engine, helping to regulate the fuel-to-air ratio.
The sensor has a built-in heater to get it up to operating temperature quickly. When the engine starts cold, the heater circuit helps the O2 sensor reach the proper temperature for accurate readings faster.
If the heater circuit fails, the sensor will take longer to heat up, delaying the engine’s ability to adjust the fuel mixture efficiently. This can result in poorer fuel economy and higher emissions.
When the P0155 code appears, it means that the powertrain control module (PCM) has detected a malfunction in the heater circuit of the O2 sensor.
This could be due to a faulty sensor, wiring issues, or a problem with the PCM itself.
The PCM continuously monitors the heater circuit, and if it detects a failure, it triggers the P0155 code and illuminates the check engine light on your dashboard.
Addressing this issue promptly is crucial because a malfunctioning O2 sensor can lead to more significant problems over time, including damage to the catalytic converter.
Ignoring this code can also result in reduced engine performance and increased fuel consumption.
In summary, the P0155 trouble code points to a problem with the heater circuit in the O2 sensor on Bank 2, Sensor 1.
This malfunction affects the sensor’s ability to quickly reach its optimal operating temperature, leading to potential engine performance issues and higher emissions.
P0155 Trouble Code Symptoms
When the P0155 code appears, you might notice the following symptoms:
- Check engine light is on
- Increased fuel consumption
- Poor engine performance
- Rough idling
- Failed emissions test
- Unusual exhaust odor
P0155 Trouble Code Causes
Several factors can trigger the P0155 code:
- Faulty O2 sensor
- Damaged or corroded wiring
- Blown fuse
- Faulty powertrain control module (PCM)
- Poor electrical connections
- Issues with the heater circuit in the sensor
How To Fix A P0155 Trouble Code
Fixing the P0155 trouble code involves diagnosing the issue and then addressing the specific cause. Here’s a step-by-step guide:
1. Scan the Vehicle
Use an OBD-II scanner to confirm the P0155 code. This will help ensure there are no additional codes affecting the diagnosis.
2. Inspect the O2 Sensor
Check the O2 sensor on Bank 2, Sensor 1. Look for any visible damage or corrosion on the sensor and its wiring.
3. Test the Heater Circuit
Use a multimeter to test the resistance of the heater circuit in the O2 sensor. Compare the reading to the manufacturer’s specifications. If the resistance is out of range, the sensor likely needs replacing.
4. Check Wiring and Connections
Inspect the wiring and connectors related to the O2 sensor. Look for any signs of damage, fraying, or corrosion. Ensure all connections are secure.
5. Check Fuses
Verify that the fuses related to the O2 sensor’s heater circuit are intact. Replace any blown fuses and check if the code clears.
6. Replace the O2 Sensor
If the sensor is faulty, replace it with a new one. Ensure it is the correct part for your vehicle model.
7. Test the PCM
In rare cases, the powertrain control module (PCM) might be the culprit. If all other components are functioning correctly, consider having the PCM tested and, if necessary, reprogrammed or replaced by a professional.
8. Clear the Code
After making the necessary repairs, use the OBD-II scanner to clear the P0155 code. Drive the vehicle to see if the check engine light returns.
By following these steps, you can diagnose and fix the P0155 trouble code, ensuring your vehicle runs smoothly and efficiently.
Conclusion
Now you know what the P0155 trouble code means and how to fix it.
Ever had this code pop up on your car?
Share your experience and drop any questions you have in the comments!
