P0057 HO2S Heater Control Circuit Low (Bank 2 Sensor 2)

The heated oxygen sensor on bank 2 is the downstream sensor 2 behind the (first) catalytic converter, used mainly to monitor the converter. Its heating element brings it quickly to operating temperature. Typically the heater receives battery voltage via a fuse, and the engine control module switches the ground side with a pulsed signal while checking that the circuit state matches the command. P0057 means the control module measures too low a voltage or current in the heater control circuit, for example because of a short to ground or, depending on the system, a burnt-out element. Which physical fault sets the general, low or high code is defined by each manufacturer. Without heating, the sensor becomes ready late and catalyst monitoring may not complete. Bank 2 codes occur only on engines with two exhaust banks (V or boxer engines).

Likely causes

Symptoms

• Check engine light on
• Usually no noticeable drivability problem
• Catalyst monitor does not complete
• Emissions test or readiness check failed

Repair estimate

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

Related codes

References: law.cornell.edu, saabwisonline.com, static.nhtsa.gov, en.wikipedia.org.