P0428: Catalyst Temperature Sensor Circuit High Bank 1 Sensor 1 — what it means, the affected system and what to check before replacing parts.
Meaning, symptoms, causes and checks
Catalyst Temperature Sensor Circuit High Bank 1 Sensor 1. Basic catalogue definition; diagnostic details have not yet been reviewed.
Affected system: Powertrain
Symptoms
- Check Engine light illumination
- Decreased engine performance
- Increased fuel consumption
- Rough engine idling
- Failed emissions test
Possible causes
- Faulty catalyst temperature sensor
- Damaged or shorted sensor wiring
- Corroded sensor electrical connector
- Engine running excessively rich
- Internal engine control module failure
What to check
- Inspect the sensor connector and wiring harness for damage or corrosion
- Measure the sensor resistance using a multimeter to check against manufacturer specifications
- Check the signal voltage at the ECU connector to identify open or short circuits
- Monitor live catalyst temperature data using a diagnostic scan tool
- Inspect exhaust system components for signs of overheating or fuel contamination
Also written as: P0428-00, P042800, PO428 (some scan tools add the fault-type byte, e.g. -00).