P0057 — HO2S Heater Control Circuit Low (Bank 2, Sensor 2) | OBD-II Code

What Does This Error Mean?

Code P0057 means the heater circuit for the Bank 2, Sensor 2 oxygen sensor is reading a low voltage signal. The ECM monitors the current flowing through the sensor heater and detects when it drops too low. This is the downstream sensor on the side of the engine that does not contain cylinder 1.

Affected Models

Most V6 and V8 vehicles (2000–present)
Ford Explorer V6
Chevrolet Camaro V8
Dodge Durango V8
Toyota Highlander V6

Common Causes

A short to ground in the sensor heater circuit wiring — the wire is contacting bare metal
The Bank 2 downstream oxygen sensor has failed internally
Corroded wiring connector causing high resistance or loss of power to the heater
A poor chassis ground point for the sensor heater circuit
ECM circuit failure — the control driver for this sensor is not working

How to Fix It

Use an OBD-II scanner to confirm P0057 and read any freeze frame data. Look for other Bank 2 sensor codes stored at the same time.

Code P0056 (general heater circuit fault) alongside P0057 points more strongly to the sensor or wiring.
Check the sensor wiring harness from the Bank 2 downstream sensor back toward the firewall. Look for wires touching the exhaust system or chassis.

A grounded wire will cause the low-voltage reading that triggers P0057.
Inspect the sensor connector for bent pins, corrosion, or loose fit. Clean with contact cleaner and ensure the connector locks securely.

On high-mileage vehicles, the connector latch can break and allow the plug to work loose over bumps.
Disconnect the sensor and measure heater resistance with a multimeter. Out-of-spec readings confirm a failed sensor.

Typical spec is 2–30 ohms — consult your vehicle-specific repair manual for the exact value.
Replace the sensor if needed. Clear all codes, start the engine cold, and complete a full drive cycle before rescanning.

The heater circuit is tested during warmup from a cold start — this is the most important part of the drive cycle.

When to Call a Professional

If you have replaced the sensor and repaired any visible wiring damage and P0057 persists, a shop will need to trace the full wiring circuit with an oscilloscope or multimeter. ECM repairs or replacements are not DIY-friendly. Expect $150–$400 at a shop for a full diagnosis.

Frequently Asked Questions

How is P0057 different from P0056?

P0056 is a general heater circuit fault — something is wrong but no direction (high or low) is specified. P0057 tells you specifically that the circuit is reading low. This narrows the likely cause to a short to ground or a failed sensor drawing too little current.

Can road salt and moisture cause P0057?

Yes. Moisture and road salt are major causes of wiring corrosion on the underside of vehicles. The oxygen sensor wiring runs along the exhaust system where it gets wet and exposed to corrosive debris. This is especially common in northern states where roads are salted in winter.

Will P0057 turn on the check engine light?

Yes. P0057 will illuminate the check engine light (MIL — malfunction indicator light). The light will stay on until the fault is repaired and the code is cleared or until the ECM runs enough self-tests to confirm the fault is gone.