Heated Oxygen Sensor (HO2S) Heater Circuit Low Voltage Bank 2 Sensor 2
The oxygen sensor heater on bank 2, sensor 2 isn't getting enough electrical power to warm up properly. Think of it like a car engine that won't start because the battery is too weak to turn the starter motor.
The ECM monitors the voltage supplied to the HO2S heater circuit on bank 2, sensor 2 (post-catalytic converter). The heater must reach operating temperature quickly so the sensor can provide accurate readings for fuel trim adjustment. If heater voltage drops below threshold, the ECM cannot trust sensor data and sets a fault.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Heater Supply Voltage | 12-14V at idle | Below 8V or intermittent supply |
| Heater Current Draw | 0.5-2.0 amps | Below 0.3A or open circuit |
Code P0057 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P0057 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.