OBD codes / P0057
P0057
ModerateO2 Sensor Heater Control Circuit Low (Bank 2, Sensor 2)
No driving restrictions come with P0057 — the downstream heater fault doesn't touch fueling, power, or safety. It's an inspection-and-warning-light problem: schedule the fix at your convenience, ideally comfortably ahead of any emissions test so readiness monitors have time to complete afterward.
What this code means
Decoding the position first: Bank 2 is the cylinder bank without cylinder 1 (so this code lives on V6/V8/flat engines, not most inline-4s), and Sensor 2 is the downstream oxygen sensor mounted after that bank's catalytic converter. The sensor's built-in heater gets it to operating temperature within seconds of start-up so converter monitoring can begin early; the sensor itself has no significant role in fuel mixing. P0057 means the computer found voltage in that heater's control circuit lower than expected — the standard interpretations being a short to ground in the wiring or a heater element that has failed open. Real-world experience puts an internally failed sensor at the top of the cause list, with corroded underbody connectors and chafed or salt-damaged harness sections close behind, and the heater fuse as an occasional easy win. The check-engine light is typically the only thing a driver ever notices.
Symptoms you might notice
- Check-engine light, usually the sole symptom
- No change in drivability or fuel economy
- Vehicle fails OBD emissions testing while the code is set
What it costs to fix
Typical range: $125–$400 · about ~0.3–1.2 hrs of labor
| If the cause is… | Part | Labor |
|---|---|---|
| Downstream oxygen (O2) sensor | $30–$200 | ~0.3–1.2 hrs |
| Wiring / connector repair | $10–$120 | ~0.5–1.5 hrs |
| Heater-circuit fuse | $1–$10 | ~0.1–0.3 hrs |
A straightforward job on most vehicles — the sensor is usually visible from underneath and the part is on the cheaper end. Costs climb mainly with rust-seized sensors, tight packaging around the converter, or a wiring fault that takes time to locate.
The price swings on which cause it turns out to be — so confirm the cause before paying. Diagnose P0057 for my exact vehicle →
Frequently asked
Where exactly is the sensor for P0057 on my car?
After the catalytic converter on the Bank 2 side — the cylinder bank that doesn't include cylinder 1. On a V-type engine each bank has its own exhaust path, so make sure you trace the correct one; buying or replacing the Bank 1 downstream sensor by mistake is a common and frustrating error.
What does 'low' signify in this code?
The computer saw the heater control circuit sitting at lower voltage than commanded — the electrical signature of a wire shorted to ground or a heater element that has burned open inside the sensor. It's a more specific finding than the generic circuit code P0056.
What will this repair run me?
Downstream sensors are typically the affordable end of the O2 family, so a shop repair usually lands in the low hundreds all-in, and a DIY sensor swap can cost just the part. A fuse or connector fix, when that's the cause, is dramatically cheaper.
Does P0057 affect an emissions test even though the car runs fine?
Yes. OBD testing checks the computer, not the tailpipe feel — an active code and lit light are an automatic fail, and the oxygen-sensor-heater monitor must report complete and passing after repair. Running fine and passing inspection are separate questions here.
Seeing P0057 on your car? Get a diagnosis specific to your exact year, make and model.
Diagnose P0057 for my vehicleRelated trouble codes
Don’t have a scanner yet? A ~$25 Bluetooth adapter reads codes like P0057 from your phone — see our honest guide to the best OBD2 Bluetooth adapters.
Generic OBD-II reference. Manufacturer-specific behavior varies — confirm with a scan tool and, for safety-related codes, a professional inspection.