P0057 OBD-II Trouble Code: HO2S Heater Control Circuit Low (Bank 2 Sensor 2)

P0057 trouble code definition

P0057 is a code that sets when the powertrain control module senses that the voltage is low on the bank 2 sensor 2 oxygen sensor.

What the P0057 code means

When a P0057 trouble code sets it means that the powertrain control module has detected a fault, specifically low voltage, on the heater control circuit for the bank two sensor two oxygen sensor.

What causes the P0057 code?

• The most common cause of the P0057 trouble code is a faulty bank 2 sensor 2 oxygen sensor.

• Some other possible causes are faulty powertrain control modules or damage to the wiring in the heater control circuit.

What are the symptoms of the P0057 code?

There are no symptoms that you can feel from a P0057 trouble code. Since the fault is in the heater circuit this means that this sensor won’t be warmed up to operating temperature in a timely manner which will increase emissions during a cold start situation.

How does a mechanic diagnose the P0057 code?

Diagnostics vary based on manufacturer but the first step for myself is to inspect the wiring going to the bank 2 sensor 2 oxygen sensor. It is a common problem to find damage to the wiring or connectors from road debris or accidents.

Once it is confirmed that there is no damage to the wiring, it is time to check the integrity of the heater in the bank 2 sensor 2 oxygen sensor itself. This is done by disconnecting the oxygen sensor and using an ohmmeter to measure the resistance of the heater. The specification can vary depending on the manufacturer but it is generally around four to five ohms. If you see OL (out of limit) or INF (infinite) resistance that means the heater is burned out and the sensor must be replaced. Most times you will find that the heater circuit in the sensor itself is burned out.

If your sensor is ok you need to check the wiring from the powertrain control module to the sensor connector. You will have to unplug the connector at the PCM and measure the resistance of the circuit from end to end. You should see less than an ohm of resistance or very close to an ohm. A few ohm could be enough to cause a problem. This amount of resistance could be caused by a wire that is partially broken inside of the insulation. If this is the case the wire will need to be replaced.

If no problem is found with the wiring the problem is most likely a faulty powertrain control module. The powertrain control module controls the circuit by grounding the circuit. It is possible that over time the switch in the powertrain control module could build up corrosion or get burned. These will increase the resistance of the circuit and cause the P0057 trouble code to set.

Common mistakes when diagnosing the P0057 code

The most common mistake made when diagnosing this trouble code is simply assuming that the oxygen sensor is bad and replacing it without performing and diagnostics. The vast majority of the time the problem will be fixed, but there are situations when this doesn’t take care of it.

How serious is the P0057 code?

• The P0057 code does not pose any risk to the vehicle.

• Vehicle emission will be increased during a cold start but once the sensor is warmed up by the exhaust it will work normally.

What repairs can fix the P0057 code?

• Replacing the bank two sensor two oxygen sensor would be the number one most popular repair for this code.

• Next would be some sort of wiring or connector repair due to damage from road hazards.

• Another possible repair would be replacing a faulty powertrain control module.

Need help with a P0057 code?

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