P0057 - HO2S Heater Control Circuit Low (Bank 2, Sensor 2)
Last updated:
System
Powertrain (Engine & Gearbox)
Related Fault Codes
Technical Description
Diagnostic Trouble Code (DTC) P0057 is set when the Engine Control Module (ECM) detects a low voltage condition in the heater control circuit for the Heated Oxygen Sensor (HO2S) located on Bank 2, Sensor 2. The sensor heater is essential for bringing the oxygen sensor to its operating temperature rapidly to minimize cold-start emissions. The ECM monitors the heater circuit's current draw; a 'low' state typically indicates a short to ground or an extremely low resistance in the heater element or its wiring, preventing the circuit from operating as commanded.
Possible Causes
Faulty heater element within the oxygen sensor (internal short)
Short to ground in the wiring harness between the sensor and ECM
Corroded or damaged electrical connector/pins
Faulty Engine Control Module (ECM) internal driver circuit
Blown fuse or faulty relay in the oxygen sensor heater supply circuit
Symptoms
Recommended Solution
- Visual Inspection: Check the wiring and connectors for Bank 2, Sensor 2 for any signs of damage, melting, or corrosion.
- Resistance Test: Disconnect the sensor and measure the resistance (Ohms) across the heater terminals (typically the two wires of the same color). Most sensors should read 5-20 Ohms. 0 Ohms indicates a short, while O.L. indicates an open circuit.
- Voltage Check: Verify that 12V battery power is supplied to the heater circuit at the harness connector when the key is on/engine running. Check the ground control from the ECM using a test light or oscilloscope.
- Sensor Replacement: If the heater element resistance is incorrect, replace the oxygen sensor with an OEM-spec part.
Mechanic's Tip
Before replacing expensive components, always double-check wiring and connections. 80% of all sensor faults are actually due to corroded contacts or broken wires.
Do you also have
other fault codes?
See how P0057 connects with your other fault codes. Our advanced analysis tool identifies causal relationships and root causes directly.