Fault-Code Library · Oxygen sensing
P0030: Heated oxygen sensor heater control circuit, bank 1 sensor 1
The ECU detects an electrical fault in the heater circuit for the upstream oxygen sensor.
Common symptoms
- •Engine warning light
- •Poor cold-running fuel control
- •Higher fuel use
- •Emissions-test failure
Likely causes
- •Failed oxygen-sensor heater
- •Blown fuse
- •Heat-damaged wiring
- •Connector corrosion
First checks
- •Check heater fuse and supply voltage
- •Inspect wiring near the exhaust
- •Measure heater resistance before replacing the sensor
Important
Exhaust components become extremely hot; test the circuit only with safe access and the correct wiring data.
A fault code identifies a detected condition, not a failed part. Confirm manufacturer-specific subcodes and live data.
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