P0427Catalyst Temperature Sensor Circuit Low Bank 1 Sensor 1
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- Some engines – mainly diesels – measure the temperature at or in the catalyst with a thermistor in a voltage divider instead of only modelling it; most makers report exhaust temperature sensors under P0544 ff, P2031 ff or P2080 ff instead. Sensor 1 of bank 1 is the first catalyst temperature sensor on the side with cylinder 1. P0427 means the signal voltage is below its lower limit – typically the signal wire is shorted to ground or the sensor is shorted internally. FCA's 3.0-litre EcoDiesel uses this sensor (middle of the oxidation catalyst and particulate filter unit), but no document available to us names this particular code.
- What you may notice
- Check engine light on
- Usually no noticeable change (substitute value from the model)
- Diesel: filter regeneration distorted or blocked, possibly further codes such as P2459 or P0420
- Likely causes
- LikelySignal wire shorted to ground (chafed)
- PossibleSensor shorted internally
- PossibleWater or corrosion in the connector
- RareEngine module
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €60 – €300
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.