P0135: the oxygen sensor heater circuit
The heater that brings the oxygen sensor quickly up to operating temperature is not working as it should. It is not urgent, but it affects fuel control until it is fixed.
Can you keep driving?
Yes. It is not urgent, but it affects fuel control until it is fixed.
What the code means
Oxygen sensors have to reach a certain temperature to measure accurately. The heater element gets them there faster, especially on a cold start.
Common causes
- A faulty heater circuit in the sensor
- A break or a poor connection in the wiring
- A fuse
What to do now
- Ask for the fuse and the wiring to be checked before the sensor is replaced.
- Note whether the code appears particularly on cold mornings.
- If your winters are cold, deal with it sooner rather than later.
What people often get wrong
Assuming no symptoms means no consequence. The sensor measures inaccurately until it is hot, and in a cold climate that means most of your driving.
When the car must go to a workshop
A failed heater circuit rarely gives a noticeable symptom while driving, so it tends to get left too long.
Read next
This page is general information and does not replace a professional assessment. Symbols, codes and behaviour vary between makes. Always check the handbook for your own car.
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