P CODES (POWERTRAIN) P0100 - P0199 P0155

    Definition of Trouble Code P0155

    Trouble code P0155 refers to a malfunction in the oxygen sensor heater circuit, specifically affecting Bank 2 Sensor 1. The oxygen sensor monitors exhaust gases to help regulate the air-fuel mixture for optimal engine performance and reduced emissions. The heater circuit warms up the sensor to reach its operating temperature faster, improving efficiency. When the engine control module (ECM) detects an issue with the heater circuit, it triggers the P0155 code.

    Diagnosing Trouble Code P0155

    To diagnose trouble code P0155, follow these steps:

    1. Connect an OBD-II scanner to the vehicle's diagnostic port and verify the presence of the P0155 code. Record any additional codes, as they may be related.

    2. Visually inspect the wiring and connections related to Bank 2 Sensor 1 oxygen sensor. Look for damaged, corroded, or disconnected wires and connectors.

    3. Using a digital multimeter, check the resistance of the oxygen sensor heater element. Compare the reading to the manufacturer's specifications. A significantly higher or lower resistance value may indicate a faulty heater element.

    4. Check the oxygen sensor's heater circuit voltage by probing the wiring harness with the multimeter. Ensure the voltage is within the manufacturer's specifications.

    5. Examine the vehicle's fuses and relays related to the oxygen sensor heater circuit. Replace any damaged or blown fuses.

    Repairing Trouble Code P0155

    To repair the issue causing the P0155 code, follow these steps based on the diagnostic findings:

    1. If the wiring and connections are damaged, corroded, or disconnected, repair or replace them as necessary.

    2. If the oxygen sensor heater element's resistance is out of specification, replace the oxygen sensor (Bank 2 Sensor 1).

    3. If the heater circuit voltage is not within the manufacturer's specifications, check the wiring between the oxygen sensor and the ECM for damage or shorts. Repair or replace as necessary.

    4. If any fuses or relays related to the oxygen sensor heater circuit are damaged or blown, replace them.

    5. If the issue persists after addressing the above steps, consult a professional mechanic for further assistance, as the ECM may be faulty and require replacement.


    Trouble code P0155 is related to the oxygen sensor heater circuit malfunction in Bank 2 Sensor 1. Proper diagnosis and repair are crucial for optimal engine performance and emissions control. By following the steps provided, you can effectively diagnose and repair the issue causing the P0155 code. If you are not comfortable with these procedures or the problem persists, consult a professional mechanic for assistance.

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