P0057
HO2S Heater Control Circuit Low (Bank 2 Sensor 2)
The engine computer sees the heater circuit for the rear oxygen sensor on bank 2 staying too low. That usually means the heater is open, the power feed is weak, or the wiring is damaged. The rear sensor then warms up too slowly to support emissions monitoring correctly.
- SEV
- 3/5
- DRIVE
- CAUTION
- DIY
- $15-$150
- SHOP
- $120-$450
01 / Definition
P0057 means the PCM detected a low-voltage condition in the heater control circuit for Bank 2 Sensor 2. This is the downstream oxygen sensor after the catalytic converter on the bank opposite cylinder 1. The most common causes are an open heater element, blown fuse, damaged wiring, poor connector contact, or a short to ground.
02 / Drive status
With caution. The vehicle is usually still drivable, but the rear oxygen-sensor monitor and emissions readiness may not work correctly. Repair it soon so the warning light does not mask a separate catalyst or fuel-system issue.
03 / Symptoms
- Check engine light on
- Failed emissions test
- O2 heater monitor incomplete
- Reduced catalyst-monitoring accuracy
- Usually no major change in how the vehicle drives
04 / Causes
| 1 | Open or failed heater element in the Bank 2 Sensor 2 oxygen sensor | high |
|---|---|---|
| 2 | Blown fuse or weak power feed to the rear O2 heater circuit | high |
| 3 | Damaged, corroded, or loose wiring or connector at the downstream sensor | high |
| 4 | Short to ground on the heater control side | medium |
| 5 | PCM driver fault | low |
05 / Diagnostic sequence
- 01Verify P0057 and check for related downstream oxygen-sensor and heater codes.
- 02Inspect the Bank 2 Sensor 2 connector and harness for road damage, corrosion, or melted insulation.
- 03Test heater-circuit fuse and relay operation, and confirm voltage reaches the sensor connector.
- 04Measure heater resistance and compare it with manufacturer specification.
- 05Check the control side of the heater circuit for a short to ground or high resistance.
- 06Repair the harness or connector and clear the code to verify monitor operation.
- 07Replace the sensor if the heater element is open and the rest of the circuit tests correctly.
06 / Repairs
| 1 | Repair damaged wiring, terminals, or connector issues at Bank 2 Sensor 2 | $15-$120 |
|---|---|---|
| 2 | Replace the blown fuse or failed relay supplying the rear O2 heater circuit | $10-$80 |
| 3 | Replace the Bank 2 Sensor 2 oxygen sensor if the heater circuit is open | $60-$240 |
| 4 | Repair PCM control-circuit faults after external electrical faults are ruled out | $120-$500 |
07 / Related codes
08 / FAQ
Is P0057 the same as P0157?
No. P0057 is the rear sensor heater circuit staying low, while P0157 is the rear sensor signal circuit reading low voltage.
Can a rear O2 heater fault affect emissions readiness?
Yes. A slow-heating downstream sensor can delay monitor completion and cause emissions-test failure.
Will the car usually still drive with P0057?
Yes, but the warning light should still be addressed soon because monitoring accuracy is reduced.