P2000

NOx Adsorber Efficiency Below Threshold Bank 1

P2000 is a generic OBD-II powertrain diagnostic trouble code: NOx Adsorber Efficiency Below Threshold Bank 1. It is logged by the engine control unit when the scr/adblue monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.

Code
P2000
Group
Powertrain
System
SCR/AdBlue
Severity
Warning (MIL on)
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What P2000 means

P2000 indicates that the NOx adsorber (also known as a NOx trap or Lean NOx Trap, LNT) on bank 1 is operating below the minimum efficiency threshold. NOx adsorbers are used predominantly in lean-burn gasoline direct injection and some diesel applications to store nitrogen oxides during lean operation and then reduce them during periodic rich purge events. The ECM evaluates adsorber efficiency by comparing NOx sensor readings upstream and downstream of the catalyst.

When the downstream NOx sensor detects NOx levels disproportionately high relative to upstream values, or when the adsorber reaches saturation before the expected storage capacity is met, the ECM concludes that the NOx conversion efficiency is insufficient. This can stem from catalyst degradation due to age or thermal damage, sulfur poisoning of the adsorber substrate, or related issues with the air-fuel mixture delivery that prevent proper purge cycles.

Diagnosis should begin with checking for exhaust system leaks that could dilute sensor readings and confirming NOx sensor accuracy before condemning the adsorber catalyst. Sulfur desulfation procedures, if supported, should also be attempted before replacement.

Common causes

Most-frequently reported root causes when P2000 is logged.

  • 1
    Aged or thermally damaged NOx adsorber catalyst with reduced storage capacity.
  • 2
    Sulfur poisoning of the adsorber substrate from high-sulfur fuel.
  • 3
    Faulty upstream or downstream NOx sensor providing inaccurate efficiency data.
  • 4
    Exhaust system leak between the upstream and downstream NOx sensors skewing readings.
  • 5
    Improper air-fuel ratio control preventing effective rich purge cycles.
  • 6
    Rich purge event frequency or duration insufficient to regenerate the adsorber.
  • 7
    Engine oil burning contaminating the catalyst substrate.

Symptoms drivers notice

MIL illuminated.
Increased tailpipe NOx emissions, likely failing an emissions inspection.
Possible slight reduction in fuel economy if purge cycles are extended.
No immediate drivability symptoms in most cases.
Related NOx sensor codes may accompany P2000 if sensor health is compromised.

How to diagnose P2000

A typical diagnostic flow when this code is present.

  1. 1
    Retrieve all DTCs and freeze frame data; note any accompanying NOx sensor codes.
  2. 2
    Inspect for exhaust leaks upstream and downstream of the NOx adsorber that could affect sensor readings.
  3. 3
    Check the NOx sensor(s) for correct operation using live data; compare readings during lean and rich conditions.
  4. 4
    Verify fuel quality being used; confirm low-sulfur fuel is being used as specified.
  5. 5
    If the vehicle supports a desulfation or sulfur purge procedure, perform it per manufacturer guidance and re-evaluate.
  6. 6
    Review purge cycle frequency and air-fuel ratio trim data to confirm rich purge events are occurring correctly.
  7. 7
    If catalyst efficiency remains low after desulfation and sensor/leak checks pass, the adsorber requires replacement.

Vehicles where we've handled P2000

Platforms in our catalogue with confirmed P2000 coverage.

BMW 320D
2016
MB GLE350 30D

Related powertrain codes

Frequently asked questions

Is P2000 the same as a catalytic converter fault?

Not exactly. A NOx adsorber is a specialized catalyst distinct from a standard three-way catalyst. P0420 covers three-way catalyst efficiency; P2000 is specific to the NOx storage function.

Can using better fuel fix P2000?

If sulfur poisoning from high-sulfur fuel is the cause, switching to low-sulfur fuel and performing a desulfation procedure may restore adsorber efficiency.

How is the NOx adsorber different from an SCR system?

A NOx adsorber stores and then reduces NOx through rich purge cycles without requiring a separate reductant. SCR systems use injected urea (DEF) to convert NOx. The two are separate aftertreatment technologies.

Will P2000 cause the car to fail an emissions test?

Yes. Reduced NOx adsorber efficiency means higher tailpipe NOx emissions, which will typically cause failure on a NOx-measuring emissions dynamometer test.

Disabling P2000 in software

RaceTune can permanently disable P2000 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.

Permanent
The monitor is disabled in the ECU itself — not just cleared. It cannot return.
Tailored to your file
Each patch is matched to your specific software version — never a one-size-fits-all file.
Reversible
The original file is always preserved. Reflash the stock to return the ECU to factory state.

ECUs with a P2000 disable in our catalogue

Confirmed coverage from our recipe database — we support many more families. Upload your file and our identifier will match it automatically.

  • Bosch EDC17C50 verified 1 software version
  • Bosch EDC17CP57 verified 1 software version

Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.

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