P0428moderate severityPowertrain
Catalyst Temperature Sensor High Input (Bank 1, Sensor 1)
on 2003 Audi A6 3.0L V6 · AWD
What this code means
The PCM detected an abnormally high signal from the bank 1 catalyst temperature sensor. This may indicate a short to voltage or a failed sensor.
Symptoms
- Check engine light on
- Failed emissions test
- High temperature reading
Common causes
- Faulty temperature sensor
- Short to voltage in wiring
- Open ground circuit
- Poor connector contact
Diagnostic steps
- Scan and confirm P0428
- Check sensor signal voltage
- Inspect wiring for shorts to power
- Test sensor resistance
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