Error code
OBD2 P0056
OBD2P0056
Diagnostic Trouble Code· Standard OBD-II fault code read from the vehicle's onboard diagnostics.
What it means
HO2S Heater Control Circuit.
Severity
moderateCan be driven, but may fail emissions testing.
Summary
Code P0056 indicates a malfunction in the heater control circuit of the downstream oxygen sensor (HO2S) on bank 2.
Symptoms
- Illuminated check engine light
Common Causes
- Problem on the ground side of the O2 sensor heater circuit
- Problem on the power side of the O2 sensor heater circuit
- High resistance in the O2 sensor heater element
- Open circuit in the O2 sensor heater element
Diagnosis
- Test the heater circuit wiring for power and ground using a digital multimeter.
- Check the sensor heating element for high resistance or an open circuit.
Fixes
- Replace the faulty oxygen sensor if there is high resistance or an open circuit in the heater element.
FAQ
What does P0056 mean?
P0056 indicates a problem with the heater control circuit of the downstream oxygen sensor on bank 2.
How do I diagnose P0056?
Use a multimeter to test for power and ground in the O2 sensor heater circuit, then check the heating element for resistance or an open circuit.
Not affiliated with OBD2. Answer summarized from the manufacturer's manual linked above; consult that source for the authoritative procedure.
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