What does code P0135 mean?
P0135 means there is a fault in the heater circuit of the Bank 1 Sensor 1 O2 sensor, the one before the catalytic converter. The heater warms the sensor quickly so the fuel mixture is right soon after starting.
Why does code P0135 appear?
- The heater inside the sensor has failed. This is the most common cause.
- The heater fuse has blown.
- The sensor's wire or plug near the hot exhaust is damaged.
What can you safely check for P0135?
- Find the O2 sensor heater fuse in your car's manual and check it. If it has blown, fit a new one of the same amp rating. If it blows again, have a mechanic look.
- Write down every code the scanner shows, not just this one. Do it before clearing them, because the other codes help the mechanic find the real cause faster.
Is it safe to drive with P0135?
You can usually keep driving, but fuel use may rise and other codes may follow. Get it fixed within a few weeks.
Safety: never remove the radiator cap on a hot engine; boiling coolant can burn you. Keep your hands away from the fan and belts while the engine runs. If you smell fuel, switch off, keep any flame or cigarette away and call a mechanic.
When should you call a mechanic?
If the fuse is fine and the code returns, have a car mechanic (mistri) check it. They will test the heater and wiring with a meter and tell you whether the sensor needs replacing or just the wiring needs repair.