O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 1)
What it means
An oxygen sensor only reads accurately when hot, so it contains a built-in heater to bring it up to temperature quickly. This code means the heater circuit is open or drawing abnormal current.
Symptoms3
- Check engine light on.
- Slightly higher fuel use after cold starts.
- Usually no noticeable effect on driving.
Possible causes4
- Burned-out sensor heater, the most common cause.
- Blown heater circuit fuse.
- Damaged sensor connector or wiring.
- Fault in the control circuit inside the engine computer (rare).
How to diagnose and fix5
- Check the oxygen sensor heater fuse.
- Inspect the sensor connector and wiring.
- Measure heater resistance against the specification.
- Replace the sensor if the heater is open.
- If the fuse blows again, look for a short in the wiring.
Repair cost
In Saudi riyals; the highlighted part is the expected range for this fault.
Replacing the sensor is the usual fix, priced between the first and second tier depending on the car.
Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Frequently asked questions
Can I repair just the heater?
No. The heater is built into the sensor, so the complete sensor is replaced.
Does this code harm the engine?
Not directly, but it increases emissions and fuel use in the first minutes after starting and may cause an inspection failure.
This guide is for information only and does not replace an inspection by a qualified technician. If the fault involves brakes, steering, engine temperature, electrics or refrigerant, do not attempt the repair yourself.
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