Code result
P21B2
Excessive Time To Enter Closed Loop NOx Adsorber Control
Moderate severity
What it means
The NOx adsorber control did not enter closed-loop operation within the calibrated time after engine start — typically a slow-warming NOx sensor or pre-heat heater fault.
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
NOx sensor heater weak
highOne of the most commonly reported causes for this code — check this first.
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