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CEL on 2017 Canyon SLT - P0135 Code - O2 Sensor?

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Mike T. · rep 0 · May 25, 2:39 AM · 1 replies · solved · Question

Vehicle: 2017 GMC Canyon SLT

Hey everyone, my Check Engine Light just came on in my 2017 GMC Canyon SLT (3.6L V6). I pulled the code with my OBD-II scanner, and it's showing P0135: 'O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)'.

The truck seems to be running fine, no noticeable changes in performance or fuel economy yet. What exactly does this code mean? Is this something I can tackle myself, or should I definitely take it to a mechanic?

Any advice on diagnosing or replacing this specific sensor would be great!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 2:39 AM

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ClearTheCode admin answer: The P0135 code, 'O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)', on your 2017 GMC Canyon SLT is a common diagnostic trouble code indicating an issue with the heater circuit of the upstream oxygen sensor on the bank of cylinders that includes cylinder #1.

Here's what you need to know:

  1. What it Means: Oxygen sensors require heat to function accurately and quickly, especially during cold starts. The heater circuit brings the sensor up to operating temperature rapidly. A malfunction means the sensor isn't heating correctly, which can delay its ability to provide accurate air-fuel ratio data to the engine control module (ECM).
  2. Potential Causes:
    • Faulty O2 Sensor: The heater element within the sensor itself can fail. This is the most common cause.
    • Wiring/Connector Issues: Damaged, corroded, or loose wiring/connector to the O2 sensor.
    • Blown Fuse: A fuse protecting the O2 sensor heater circuit could be blown (less common for individual sensor, more for multiple).
    • ECM Fault: Very rare, but a faulty ECM could fail to provide power to the heater circuit.
  3. DIY Diagnosis/Fix:
    • Visual Inspection: Check the wiring and connector for Bank 1 Sensor 1 (typically located before the catalytic converter on the side with cylinder #1) for any signs of damage, fraying, or corrosion.
    • Multimeter Test: If you're comfortable, you can test the resistance of the heater circuit within the O2 sensor and check for voltage at the connector (with the engine running) to confirm power supply.
    • Replacement: If the sensor itself is confirmed faulty, replacing it is often a straightforward DIY job with the right O2 sensor socket, provided it's accessible. Ensure you use a direct-fit, OEM-quality replacement.

When to See a Shop: While often a DIY fix, if you're unsure about diagnosing electrical circuits, or if the sensor is difficult to access, it's best to consult a professional mechanic. They can accurately test the sensor and its wiring, ensuring no other underlying electrical issues are present, and replace the sensor correctly. Though your truck runs fine now, prolonged driving with a faulty O2 sensor can lead to decreased fuel economy and potentially damage the catalytic converter over time.

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