Error code
OBD2 P0042
OBD2P0042
Diagnostic Trouble Code· Standard OBD-II fault code read from the vehicle's onboard diagnostics.
What it means
HO2S Heater Control Circuit.
Severity
moderateCan drive, but may fail emissions testing.
Summary
Code P0042 indicates a malfunction in the heater circuit of the downstream oxygen sensor (HO2S) on bank 1 of your engine.
Symptoms
- Illuminated check engine light
Common Causes
- Problem with the ground side of the O2 sensor heater circuit
- Problem with 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 resistance of the sensor heating element to determine if it has 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 should I do if my check engine light comes on with code P0042?
You should test the oxygen sensor's heater circuit for power and ground issues, and replace the sensor if there is high resistance or an open circuit in the heating element.
Not affiliated with OBD2. Answer summarized from the manufacturer's manual linked above; consult that source for the authoritative procedure.
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