P0155 Fault Code

O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)

• What does that mean?
• Symptoms
• Causes
• Solutions

The P0155 fault code indicates a malfunction in the oxygen sensor heater circuit for Bank 2 Sensor 1. This sensor is crucial for measuring the oxygen levels in the exhaust gases, helping to manage the air-fuel mixture and ensuring optimal engine performance. A malfunction in this system can lead to increased emissions and reduced fuel efficiency.

What are the symptoms of the P0155 code?

Common symptoms associated with the P0155 fault code may include:

• Check Engine Light (CEL) illumination on the dashboard.
• Poor fuel economy due to inefficient fuel mixture.
• Rough idling or stalling when the engine is cold.
• Increased emissions that could lead to failing an emissions test.

What causes the P0155 code?

There are several potential causes for a P0155 code, including:

• A defective oxygen sensor heater element.
• Damaged wiring or connectors leading to the sensor.
• Short circuits or open circuits in the sensor circuit.
• Faulty engine control module (ECM) that is not supplying correct voltage to the heater circuit.

How to fix P0155?

To resolve the P0155 code, consider the following steps:

1. Conduct a visual inspection of the oxygen sensor and its wiring for any obvious damage or disconnections.
2. Use a multimeter to test the heater circuit voltage and resistance to ensure it meets specifications.
3. Replace the oxygen sensor if found to be faulty or damaged.
4. Repair any damaged wiring or connectors in the sensor circuit.
5. Clear the fault code and take a test drive to verify that the issue is resolved and the Check Engine Light does not reappear.