Code result
P0423
Heated Catalyst Efficiency Below Threshold
Moderate severity
What it means
Heated (electrically warmed) catalyst on bank 1 fails efficiency monitoring. In addition to standard catalyst aging, faults in the catalyst heater control or supply can cause this code.
Is it safe to drive?
Use caution
The vehicle is usually drivable for short distances, but the problem can worsen or affect emissions. Diagnose and repair as soon as practical.
Most likely causes
Catalyst aged or contaminated
highOne of the most commonly reported causes for this code — check this first.
Catalyst heater circuit fault
mediumA plausible cause — test and verify before replacing parts.
Related help
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