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P0056 OBD-II Trouble Code: HO2S Heater Control Circuit (Bank 2 Sensor 2)

Check Engine Light

P0056 trouble code definition

The P0056 trouble code signifies that there is a problem with the heater control circuit in the bank 2 sensor 2 oxygen sensor.

What the P0056 code means

This code means that the bank 2 sensor 2 oxygen sensor is not heating up properly due to a problem in the oxygen sensor heater circuit.

What causes the P0056 code?

The P0056 trouble code is caused by an incorrect amount of resistance in the heater circuit. This is most often caused by a faulty sensor due to the high temperature that the heater operates at.

What are the symptoms of the P0056 code?

The only symptom of this code is that emission coming from the vehicle could increase due to the oxygen sensor taking longer to reach it’s operating temperature. This increase in emissions is what causes the Check Engine Light to come on so that the vehicle can be repaired as soon as possible.

How does a mechanic diagnose the P0056 code?

  • The first step in diagnostics for a P0056 trouble code is to complete a visual inspection of the wiring for the bank 2 sensor 2 oxygen sensor.

  • Many times this code can be set due to wires being damaged by being routed incorrectly or by road hazards.

  • If no problems are found during the visual inspection the next step is to use a multimeter to measure the resistance of the heater circuit in the oxygen sensor itself. The service manual for your vehicle has a ohm specification for a good sensor.

  • If the resistance of the sensor is not in spec then it is faulty and the oxygen sensor will need to be replaced.

  • If the sensor checks out ok, then we must check the resistance of the rest of the circuit from powertrain control module to the connector of the bank 2 sensor 2 oxygen sensor. A normal reading for wiring is less than half an ohm.

  • If the rest of the wiring is found to be good then the likely culprit is the powertrain control module itself.

Common mistakes when diagnosing the P0056 code

The most common mistake is not performing any diagnostics at all and simply replacing the bank 2 sensor 2 oxygen sensor. Majority of the time the sensor is the problem, but from time to time there can be other issues as I pointed out earlier.

How serious is the P0056 code?

The P0056 trouble code is not the most serious of fault codes. There is a very small chance that if conditions are just right that the powertrain control module could be damaged but it is very unlikely.

What repairs can fix the P0100 code?

The most common repairs for trouble code p0056 is the replacement of the bank 2 sensor 2 oxygen sensor or repairing the wiring in the heater circuit.

Need help with a P0100 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

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