P1278
Air Fuel Ratio Sensor 1 Bank 1 Circuit Slow Response
Severity
⚠️ MediumCan you drive?
Yes, but get it checked soon
Approx. repair cost
$33–89 (est.)
Symptoms
- Increased fuel consumption
- Reduced engine power
- Unstable idling
- Check Engine Light Is On
- Increased emissions of harmful substances
Causes
- Air-fuel ratio sensor malfunction
- Sensor contamination
- Problems in the sensor electrical circuit
- Wiring harness fault
- Sensor circuit grounding problems
How to Fix
- Check the condition of the AFR sensor
- Check the electrical circuit of the sensor for breaks and short circuits
- Clean sensor connector contacts
- Check sensor circuit grounding
- If necessary, replace the air-fuel ratio sensor