TorqueMech OBD Code Guide
P0428 - Catalyst Temperature Sensor High Input (Bank 1 Sensor 1)
The catalyst temperature sensor signal on bank 1 sensor 1 is higher than expected.
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Common Next Steps
Turn the code into the next check.
Inspect ignition coils
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Verify injector operation
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Check compression if needed
Use compression or leak-down testing when spark and fuel checks do not move the fault.
Related Inspection
Code Overview
The catalyst temperature sensor signal on bank 1 sensor 1 is higher than expected.
Common Causes
- Aging catalyst
- Exhaust leak ahead of the catalyst or sensor
- Sensor or wiring fault
- Upstream fueling or misfire problem
Diagnostic Steps
- Fix any active misfire or fueling codes first
- Check for exhaust leaks ahead of the converter
- Compare sensor data before replacing catalyst parts
Related OBD Codes
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Next Steps
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