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P0057 Code Explained: HO2S Heater Control Circuit Low Bank 2 Sensor 2 Causes, Symptoms & Fixes

P0057 code displayed on an OBD-II scanner with the Bank 2 Sensor 2 downstream oxygen sensor and heater wiring highlighted for a low-voltage circuit fault.

If your OBD-II scanner displays P0057, your vehicle’s Engine Control Module (ECM) or Powertrain Control Module (PCM) has detected a low-voltage condition in the heated oxygen sensor (HO2S) heater control circuit for Bank 2 Sensor 2.

The generic SAE definition for P0057 is:

HO2S Heater Control Circuit Low Bank 2 Sensor 2

This code indicates the ECM has detected lower-than-expected voltage or higher-than-expected current in the heater circuit of the downstream oxygen sensor located on Bank 2.

Depending on the manufacturer, Bank 2 Sensor 2 may also be referred to as:

Unlike P0056, which identifies a general heater circuit fault, P0057 specifically indicates the heater circuit voltage is lower than expected, typically because the circuit is shorted or the heater element has failed internally.

Common causes include:

Although P0057 rarely causes drivability concerns, it can increase emissions, delay catalyst monitoring, and prevent emissions readiness monitors from completing.

For additional diagnostic information, visit:

P0057 Quick Facts

ItemInformation
OBD-II CodeP0057
DescriptionHO2S Heater Control Circuit Low Bank 2 Sensor 2
CategoryPowertrain
SystemEmissions
SensorBank 2 Sensor 2
Sensor LocationDownstream (After Catalytic Converter)
SeverityLow to Moderate
Safe to Drive?Usually
Typical Repair Cost$75–600

What Does P0057 Mean?

P0057 indicates the ECM has detected lower-than-normal voltage in the heater control circuit for the Bank 2 Sensor 2 oxygen sensor.

Most oxygen sensor heater circuits receive battery voltage while the ECM controls the ground side.

If the circuit becomes shorted or current increases beyond the calibrated limit, the ECM sees the voltage drop below its expected value and stores P0057.

This code often points toward:

What Is Bank 2 Sensor 2?

Bank 2 is the side of the engine that does not contain cylinder number one.

Sensor 2 is the oxygen sensor located after the catalytic converter.

Its primary responsibilities include:

Unlike upstream oxygen sensors, the downstream sensor has very little effect on fuel delivery.

Why Does the Downstream Oxygen Sensor Have a Heater?

The downstream oxygen sensor must reach operating temperature quickly after startup.

The built-in heater allows the ECM to:

Without a functioning heater, the ECM must wait for exhaust heat to warm the sensor.

How the Heater Circuit Works

A typical heater circuit includes:

The ECM monitors:

If current becomes excessive and voltage drops below expected values, P0057 is stored.

What Does “Circuit Low” Mean?

“Circuit Low” means the ECM detects lower-than-expected voltage in the heater circuit.

Common causes include:

Unlike P0058, this code generally indicates too much current flow, not too little.

How the ECM Detects P0057

The ECM performs heater diagnostics during cold starts.

It compares:

The ECM stores P0057 when it detects:

Depending on manufacturer strategy, the MIL may illuminate immediately or after several drive cycles.

P0056 vs P0057 vs P0058

CodeDescription
P0056Heater Control Circuit
P0057Heater Control Circuit Low
P0058Heater Control Circuit High

Generally:

Symptoms of P0057

Common symptoms include:

Most drivers experience little or no change in drivability.

Common Causes of P0057

1. Shorted Heater Element

The heater inside the oxygen sensor develops an internal short.

This is one of the most common causes.

2. Wiring Shorted to Ground

The heater wiring may contact:

Heat damage frequently causes insulation failure.

3. Melted Wiring Harness

Because downstream sensors operate near extremely hot catalytic converters, melted wiring is common.

4. Water Intrusion

Moisture entering the connector can create conductive paths that lower circuit voltage.

5. Damaged Connector

Inspect for:

6. Incorrect Oxygen Sensor

Universal oxygen sensors sometimes have heater characteristics outside OEM specifications.

Use OEM-quality direct-fit sensors whenever possible.

7. Harness Damage

Look for:

8. ECM Driver Failure

Rare.

Only suspect after all external testing confirms the sensor and wiring are functioning correctly.

Is P0057 Serious?

P0057 is generally considered low to moderate severity.

The vehicle usually remains drivable.

However, delaying repairs may result in:

Can You Drive With P0057?

Yes, in most cases.

However, if the short is caused by melted wiring contacting the exhaust, repairs should be made immediately to prevent additional electrical damage.

How to Diagnose P0057

Step 1: Scan for Additional Codes

Check for:

Record freeze-frame data before clearing codes.

Step 2: Locate Bank 2 Sensor 2

Confirm:

Replacing the wrong oxygen sensor remains one of the industry’s most common mistakes.

Step 3: Inspect Wiring

Check for:

Step 4: Inspect Connector

Inspect for:

Step 5: Check Heater Resistance

Disconnect the oxygen sensor.

Measure heater resistance.

Very low resistance usually indicates an internally shorted heater.

Step 6: Verify Power Supply

Inspect:

Step 7: Check for Short to Ground

Using a multimeter, verify the heater control circuit is not shorted directly to ground.

Repair damaged wiring before replacing components.

Step 8: Perform Voltage Drop Testing

Check voltage drop across:

High current often creates abnormal voltage readings.

Step 9: Replace the Sensor if Necessary

If testing confirms a shorted heater element, replace Bank 2 Sensor 2 with an OEM-quality direct-fit oxygen sensor.

Step 10: Verify Repairs

After repairs:

  1. Clear DTCs.
  2. Perform a cold start.
  3. Monitor heater operation.
  4. Complete a drive cycle.
  5. Confirm readiness monitors complete.
  6. Verify P0057 does not return.

Common Repairs and Costs

RepairEstimated Cost
Oxygen sensor replacement$150–500
Wiring repair$100–400
Connector replacement$75–250
Heater relay replacement$50–200
Fuse replacement$10–50
Harness repair$100–500
ECM replacement$1,000–2,500+

Common Diagnostic Mistakes

Avoid these mistakes:

Vehicles Commonly Affected

P0057 commonly appears on:

Exact heater circuit designs vary by manufacturer.

How to Prevent P0057

Reduce the likelihood of P0057 by:

Frequently Asked Questions

What does P0057 mean?

P0057 indicates the ECM has detected a low-voltage condition in the heater control circuit for Bank 2 Sensor 2.

Is P0057 serious?

Usually not, but wiring shorts should be repaired quickly to prevent additional electrical damage.

Can I drive with P0057?

Yes.

Most vehicles remain safe to drive.

What causes P0057?

Common causes include:

Will replacing the oxygen sensor fix P0057?

Often yes, provided the heater element has failed.

Always inspect the wiring before replacing parts.

Is P0057 the same as P0056?

No.

P0056 is a general heater control circuit fault.

P0057 specifically indicates a low-voltage condition.

Does P0057 affect fuel economy?

Very little.

The downstream oxygen sensor primarily monitors catalyst efficiency.

Can P0057 cause an emissions failure?

Yes.

Incomplete catalyst monitoring and readiness monitors may prevent the vehicle from passing an emissions inspection.

Final Thoughts

The P0057 code indicates the ECM has detected a low-voltage condition in the Bank 2 Sensor 2 oxygen sensor heater control circuit. In most cases, the fault is caused by a shorted heater element, damaged wiring, or a short to ground within the heater circuit.

Begin diagnosis by inspecting the wiring near the catalytic converter, as heat damage is extremely common in this area. After verifying the wiring, test the heater resistance, connectors, fuse, and relay before replacing components. Prompt repairs help restore proper catalyst monitoring, reduce emissions, and ensure the vehicle completes its OBD-II readiness monitors.

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