SCR NOx Pre-Catalyst - Over Temperature Bank 1
This code means the PCM/ECM has detected a fault affecting scr nox pre-catalyst - over temperature bank 1. This can keep the emissions system from working correctly, which may raise tailpipe emissions, reduce fuel economy, and prevent readiness monitors from completing.
What You Might Notice
- Check Engine Light illuminated
- Reduced fuel economy
- Failed emissions or readiness monitor
- Rough idle or hesitation
- Possible exhaust smell or smoke
Most Common Causes
- 1
Aging or damaged catalytic converter
- 2
Oxygen sensor fault affecting catalyst monitoring
- 3
Exhaust leak ahead of the catalyst
- 4
Rich/lean running condition that overheats the catalyst
- 5
Engine misfire damaging the converter
How to Diagnose It
- 1
Check Aging or damaged catalytic converter — Inspect for signs of failure and test before replacing.
- 2
Check Oxygen sensor fault affecting catalyst monitoring — Inspect for signs of failure and test before replacing.
- 3
Check Exhaust leak ahead of the catalyst — Inspect for signs of failure and test before replacing.
- 4
Check Rich/lean running condition that overheats the catalyst — Inspect for signs of failure and test before replacing.
- 5
Check Engine misfire damaging the converter — Inspect for signs of failure and test before replacing.
How to Fix It
- 1
Inspect the sensor, valve, heater, and related hoses or pipes
- 2
Repair wiring or connector damage
- 3
Clean carbon buildup or repair leaks/restrictions
- 4
Replace the failed emissions component if testing confirms it
- 5
Clear the code and run the monitor to verify the fix
Need a deeper diagnosis?
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