What causes a P2001 code?

P2001 can be triggered by several issues — see the verified probable causes and step-by-step diagnostics shared by mechanics and owners on OBDIY.

Can I drive with a P2001 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with P2001 active.

Follow the step-by-step diagnostic on this page, then read the verified fixes contributed by other Heavy Truck owners — the answer marked "Verified Cause" worked for the original poster.

OBDIY

OBD-II

P2001

NOx Adsorber Efficiency Below Threshold Bank 2

What it means

The engine control module (ECM) monitors the performance of the Nitrogen Oxide (NOx) adsorber/catalyst system. This code indicates that the Bank 2 catalyst efficiency has dropped below the minimum acceptable level for emissions compliance.