What does code P0423 mean?
The heated catalytic converter on bank 1 fails to reach the required efficiency level.
OBD-II Code
P0423 — Heated Catalyst Efficiency Below Threshold (Bank 1
The heated catalytic converter on bank 1 fails to reach the required efficiency level.
Common symptoms
- Persistent check engine light
- elevated emissions
Possible causes
- Damaged internal heater element
- slow or faulty oxygen sensors
Initial recommendation
Check heated catalyst operation, inspect heater circuits and oxygen sensors.
Safety notice
This information is for guidance only and does not replace a physical vehicle inspection or diagnosis by a qualified mechanic. If the vehicle has severe power loss, smoke, a fuel odor, overheating, brake or steering problems, or any unsafe behavior, avoid driving it and seek professional inspection.
Analyze this code with MecaOBD
Use the app to combine code P0423 with your vehicle's actual symptoms for more complete diagnostic guidance.
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