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P0135: O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 1)
The heater inside the front O2 sensor on bank 1 has failed.
Low Severity
$5 – $400
Can I Keep Driving with Code P0135?
Yes, the car will run fine but fuel economy suffers until the sensor warms up on its own.
What P0135 Means
Modern O2 sensors have built-in heaters to bring them up to temperature quickly. P0135 means the heater circuit is no longer working, usually a failed sensor or blown fuse.
Common Causes
- Failed O2 sensor — see repair cost
- Blown sensor heater fuse
- Damaged wiring to the sensor
Diagnostic Tips
- Check the O2 sensor heater fuse first, often a $5 fix.
- Sensor replacement is straightforward on most cars.
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Get My Free EstimateFrequently Asked Questions
Will P0135 fail emissions testing?
Yes in most states, since the sensor heater is part of the emissions system.