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P0135: Oxygen sensor heater (bank 1, sensor 1): circuit fault

The heater in the bank 1 oxygen sensor before the catalytic converter has a fault. Usually a blown fuse, the connector or the sensor itself.

Code P0135 at a glance
CodeP0135
SystemEngine and transmission
GroupP01xx, Air and fuel metering
TypeGeneric: it means the same on every make
Can you keep driving?Yes, no rush

What P0135 means

The oxygen sensor before the catalytic converter measures how much oxygen is left in the exhaust, and the ECU uses that to fine-tune the air and fuel mixture. The sensor only works when it is very hot, so it has a small built-in heater that warms it up after a cold start. This code means the heater circuit has a fault.

Most common causes

  • Blown fuse for the oxygen sensor heaters
  • Sensor connector loose or corroded
  • Broken supply or earth wire to the heater
  • Burnt-out heater element inside the sensor (the most common cause; the sensor has to be replaced)
  • Faulty relay or ECU supply to the heater

Symptoms

  • Engine warning light on
  • Slightly higher consumption on short, cold journeys
  • High emissions while the engine is cold

Can you drive with P0135?

Yes, no rush You can drive normally. When cold the mixture is controlled less precisely and the car uses a little more fuel, so do not leave the repair too long.

How to check it

Look in the handbook for the fuse that feeds the oxygen sensor heaters and check it. If it is fine, a garage can measure the heater resistance at the sensor connector: with no continuity, the sensor needs replacing.

How to read and clear P0135 with Final OBD

Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see P0135 with this same explanation and whether it’s confirmed, pending or permanent.

With Free you read this code with its short description for nothing, and clear it if the engine stores it over standard OBD. With Pro you get the full explanation, how the car was running when it was logged (revs, temperature, load) and clearing in every control unit.

Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before the ITV. It’s all in how to read and clear fault codes and in the ITV and OBD.

Similar codes

P0135 is a generic code, so it means the same on any make, for example on Audi, Fiat, Kia, Mazda, Opel / Vauxhall, Toyota. See what Final OBD does on your car in makes and models.

What does code P0135 mean?

The oxygen sensor before the catalytic converter measures how much oxygen is left in the exhaust, and the ECU uses that to fine-tune the air and fuel mixture. The sensor only works when it is very hot, so it has a small built-in heater that warms it up after a cold start. This code means the heater circuit has a fault.

Can you drive with P0135?

You can drive normally. When cold the mixture is controlled less precisely and the car uses a little more fuel, so do not leave the repair too long.

How do you clear P0135?

With an OBD2 scanner and an app like Final OBD, which clears it for free if it’s stored by the engine control unit. But clearing it only turns the light off: if the cause isn’t fixed, P0135 comes back.