Code result
P2001
NOx Adsorber Efficiency Below Threshold
Moderate severity
What it means
The lean NOx trap (LNT) on bank 2 is no longer storing or releasing NOx within the required efficiency window. Detected by the downstream NOx sensor or model-based monitor — typically caused by sulphur poisoning, thermal aging, or a failed regeneration strategy.
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
Sulphur poisoning
highOne of the most commonly reported causes for this code — check this first.
Thermal aging of washcoat
mediumA plausible cause — test and verify before replacing parts.
Related help
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