Powertrain, generic (extended)

P2000 NOx Adsorber Efficiency Below Threshold (Bank 1)

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

A NOx adsorber (lean NOx trap) collects nitrogen oxides while a lean-running engine produces them and turns them into nitrogen during short rich purges. P2000 reports that the trap on bank 1 no longer stores or converts enough NOx; CARB wants this flagged before tailpipe NOx passes a fixed multiple of the standard. Chrysler documents the code on 2007 to 2011 Ram 2500/3500 pickups with the 6.7 L Cummins: bulletin 25-001-13 links it, often together with P2A00/P2A01, to sooted oxygen sensors has both sensors cleaned or replaced and a heat shield added, while 18-012-12 brings revised engine software for P2000 and other codes on the 2011 trucks. Sulphur poisoning, thermal ageing or purges that never complete are further reasons. The truck usually drives normally, but NOx output rises.

Likely causes

Sooted or drifting oxygen sensors that misjudge trap loading and purges
NOx trap poisoned by sulphur or aged by heat
Engine software that sets the code without a real fault (update available on some models)
Rich purges or desulphation not completed, e.g. because of short trips

Symptoms

  • Malfunction indicator lamp on
  • Often accompanied by oxygen sensor codes P2A00/P2A01
  • No noticeable change in driveability

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€100–3,000
Time0.5–4 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

nox adsorber catalystnox sensor downstreamexhaust temperature sensor

Related codes

P2001P2A00P2A01

References: law.cornell.edu, static.nhtsa.gov, static.nhtsa.gov, en.wikipedia.org.