P0057
HO2S Heater Control Circuit Low (Bank 2 Sensor 2)
Low· Fix when convenientDIY friendlyPowertrainGeneric, all makes
What it means
The oxygen sensor heater control circuit at Bank 2 Sensor 2 is reading low voltage, usually an open heater element, a blown fuse or a broken wire. This is the downstream oxygen sensor on bank 2, mounted after the catalytic converter. Its main job is to check that the converter is working.
Is it safe to drive?
Safe to drive. It mainly affects emissions and cold-start economy.
Symptoms
- Check engine light on
- Slightly worse fuel economy after cold starts
Probable causes
Most likely first
- 1Heater element open inside the sensor (most common)
- 2Blown heater fuse
- 3Open heater feed or control wire
How to diagnose it
Work through these in order before buying parts
- 1Record the code and its freeze frame data (speed, load, temperature when it set), then clear it and see if it comes back.
- 2Check the heater fuse.
- 3Measure heater resistance at the sensor; an open circuit means the sensor must be replaced.
- 4Check for technical service bulletins (TSBs) or software updates for your make and model; some codes have known factory fixes.
Common fixes
- Replace the oxygen sensor
- Replace the fuse or repair the wiring
This information is general guidance for all makes. Exact causes, specifications and procedures vary by vehicle, so confirm with your service manual or a qualified mechanic before replacing parts.