HO2S Heater Control Circuit (Bank 1 Sensor 1)
The lambda sensor only reads well when it is very hot, so it has a built-in heater that warms it straight after starting.
What the car has detected
The ECU does not see the right current in the front sensor’s heater: it is usually open or has a loose wire.
It is not dangerous, but the car may use more fuel and fail the inspection. Have it checked when you can.
Symptoms
- Engine warning light on
- Higher fuel use
Possible causes
- Open lambda sensor heater
- Broken or shorted wire, or a loose or corroded connector
- Blown fuse
Checks for the garage
- Measure the sensor heater resistance
- Check the sensor wiring and connector
- Check the circuit fuse
Next step
Ask for the front lambda sensor heater and its wiring to be measured. If the heater is open, the sensor is replaced.
You can keep using the car and book a visit without hurry.