Diagnostic guide for P0155

Diagnostic Guide for P0155 - O2 Sensor Heater Circuit Malfunction

The P0155 code indicates a malfunction in the heater circuit of the heated oxygen sensor located in Bank 2, Sensor 1. The goal of this diagnostic guide is to identify the root cause of the issue, which may involve inspecting the sensor, wiring, and related components.

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Difficulty

Intermediate

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Estimated Time

30-60 Minutes

Estimated Diagnostic Cost

$0-$100

Typical shop charge to perform this diagnostic process. Repair parts and labor are not included.

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Tools Needed

OBDII scanner, multimeter, wiring diagram, basic hand tools

Safety Notes

Ensure the engine is off and cool before starting. Use caution when working around the exhaust system and electrical components.

Step 1

Check for Additional Codes

Instruction Use an OBDII scanner to check for any additional trouble codes that may be present.

Expected result No additional codes or related codes are found.

If Pass If no additional codes are present, proceed to the next step.

If Fail If other codes are present, address those issues first as they may be related.

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Coddy can help with this step only. Tell me what you tested or what result you got.

Step 2

Inspect the O2 Sensor Connector

Instruction Visually inspect the connector for the heated oxygen sensor for signs of corrosion, damage, or water intrusion.

Expected result Connector appears clean and undamaged.

If Pass If the connector is in good condition, proceed to check the fuse.

If Fail If the connector is damaged or corroded, repair or replace it as necessary.

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Step 3

Check the O2 Sensor Fuse

Instruction Locate and check the fuse associated with the heated oxygen sensor circuit for continuity using a multimeter.

Expected result Fuse is intact and shows continuity.

If Pass If the fuse is good, proceed to test the sensor's heater circuit.

If Fail If the fuse is blown, replace it and recheck the system for codes.

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Coddy can help with this step only. Tell me what you tested or what result you got.

Step 4

Test the O2 Sensor Heater Circuit

Instruction With the engine running, use a multimeter to measure the voltage at the O2 sensor heater circuit terminals.

Expected result Voltage reading is within the manufacturer's specified range.

If Pass If voltage is within range, the sensor may be faulty; proceed to the next step.

If Fail If voltage is out of range, inspect the wiring for shorts or opens and repair as necessary.

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Step 5

Evaluate the O2 Sensor Functionality

Instruction If all previous steps pass, consider testing the O2 sensor's functionality by monitoring its output voltage while the engine is running.

Expected result Sensor output voltage fluctuates as expected with engine operation.

If Pass If the sensor operates correctly, the issue may lie with the ECM; further diagnostics may be needed.

If Fail If the output is static or out of range, replace the heated oxygen sensor.

Ask Coddy about this step

Coddy can help with this step only. Tell me what you tested or what result you got.