Code result
P2423
HC Adsorption Catalyst Efficiency Below Threshold Bank 1
Moderate severity
What it means
The ECU determines that the hydrocarbon adsorption catalyst on bank 1 no longer holds enough HC during cold start to meet emission targets. Often due to ageing or thermal damage.
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 aging / thermal damage
highOne of the most commonly reported causes for this code — check this first.
Oxygen sensor drift
mediumA plausible cause — test and verify before replacing parts.
Related help
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