This is one of the most frequent OBD2 trouble codes. Read the full article below to know what it means, how to fix it, and what other codes may show related to it.
P0056 is an OBD-II Code that refers to Heated Oxygen Sensor (HO2S) 2, Bank 2, Heater control - Circuit Malfunction
A P0056 code is a general diagnostic trouble code that occurs when the PCM/ECM detects a problem with the HO2S heater control circuit on Bank 2. The bank 2 sensor 2 oxygen sensor is usually faulty when it does not heat up properly. The heating element of each sensor works to raise the operating temperature in a shorter period. As a result, the PCM takes into account earlier input signals to provide more precise fuel management and lower emissions.
The P0056 code will be set and stored in the PCM's memory, and a malfunction indicator light (MIL) will usually be illuminated when an issue occurs with the sensor number 2 located in bank 2, which is located after the Catalytic Converter (TWC) and keeps in check the efficiency of the converter.
Common causes for this code include:
- A shorted, open, or otherwise damaged circuit
- Faulty Heated Oxygen Sensor
- Heated Oxygen Sensor (H2OS) damaged circuit fuse
- Bad Engine Control Module (Rare)
The symptoms of a P0056 code are:
- Illuminated Check Engine Light
- Decreased fuel efficiency
To diagnose a P0056 DTC code, a technician would:
- Scan for codes in the ECM and look at the freeze frame data for failure.
- Visually inspect the wiring and connectors for damage or shorts.
- Check the valve body for any damage or leaks.
- Test the input and turbine speed sensors for proper function.
- Check the transmission fluid level and quality.
The following are some of the most common mistakes that a technician may make when diagnosing a P0056 code:
- Not thoroughly inspecting all the wiring and connectors for damage.
- Not checking the valve body for damage or leaks.
- Not testing the input and turbine speed sensors for proper function.
- Failing to properly diagnose the code.
How serious is this?
The P0056 fault code is not the most serious of error messages, and if circumstances are right, the engine control module may be damaged, but it's extremely rare.
What repairs can fix the code?
The following are solutions that may fix this problem:
- Repair or replace any wiring that is damaged
- Replace the Heated Oxygen Sensor
- Replace the fuse for the Heated Oxygen Sensor
- Replace the Engine Control Module (Rare)
A P0056 is related to and may be accompanied by the following codes:
P0057 - Heated Oxygen Sensor (HO2S) 2, Bank 2, Heater control - Voltage too low
P0058 - Heated Oxygen Sensor (HO2S) 2, Bank 2, Heater control - Voltage too high
P0059 - Heated Oxygen Sensor (HO2S) 2, Bank 2, Heater control - No activity detected
In conclusion, the P0056 code is a diagnostic trouble code that refers to a problem with the heated oxygen sensor heater control circuit on Bank 2. If this code is present, a technician would need to inspect the wiring and connectors for damage or shorts, test the input and turbine speed sensors for proper function, and check the valve body for any damage or leaks. If everything checks out, the most likely solution would be to replace the heated oxygen sensor.