Emissions

P0057 — O2 Sensor Heater Control Circuit Low (Bank 2, Sensor 2)

Severity: low Safe to drive

What P0057 means

The engine control unit switches the heater in the downstream (post-catalytic converter) oxygen sensor on Bank 2 and monitors the control circuit voltage. The heater brings the sensor to operating temperature quickly so it reads accurately. P0057 sets when the circuit voltage is lower than expected, usually from a short to ground, a failed heater element in the sensor, or a power supply problem.

Symptoms

  • Check Engine light on
  • Slightly worse fuel economy in some cases
  • Emissions test failure
  • Occasionally a rough idle
  • Other codes for the downstream oxygen sensor or catalyst efficiency

Possible causes

  1. Failed heater element in the Bank 2 Sensor 2 oxygen sensor
  2. Damaged wiring insulation, short to ground, or corroded connector pins
  3. Blown fuse feeding the oxygen sensor heater
  4. Loose or poor connection at the sensor plug
  5. Faulty heater driver inside the PCM (rare)

How to diagnose

  1. Scan for codes and freeze frame data and look for other oxygen sensor codes
  2. Confirm which sensor is Bank 2 Sensor 2 so it isn't confused with Bank 1
  3. Check the fuse and relay that power the oxygen sensor heaters
  4. Inspect the harness and connector for chafing, heat damage and corrosion
  5. Measure heater resistance at the sensor and compare it to the vehicle's specification
  6. Check for power at the connector and the PCM control signal with the ignition on or during warm-up
  7. With the connector unplugged, test the control wire for a short to ground
  8. Look for exhaust leaks near the sensor

Common fixes

  • Replace the Bank 2 Sensor 2 oxygen sensor
  • Repair the damaged wire or replace the connector
  • Replace the blown fuse after finding what overloaded it
  • Replace or reprogram the PCM if the heater driver is confirmed faulty

Questions and answers

What does P0057 mean?

It means low voltage in the heater control circuit of the Bank 2 downstream oxygen sensor. The sensor itself or its wiring is the most common culprit.

Can I drive with code P0057?

Usually yes, because drivability is normally unaffected. Don't put the repair off for long, though, as it affects emissions and could cause an inspection failure.

How do I quickly find the cause of P0057?

Start with the fuse and a visual check of the sensor connector and wiring, then measure the heater resistance. If it is out of spec, replace the sensor.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.