Code Definition

P2000 — NOx Adsorber Efficiency Below Threshold - Bank 1

System: Powertrain  |  Type: Generic (OBD-II Standard)  |  Make: Mercedes-Benz

About P2000

P2000 is a generic (obd-ii standard) powertrain diagnostic trouble code recorded for Mercedes-Benz vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P2000 is stored, the module has detected a signal or supply voltage lower than the expected operating range; and a bank-specific fault, meaning it applies only to one cylinder bank of a multi-bank engine.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

Because P2000 is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

The Powertrain Control Module (PCM) monitors the efficiency of the Bank 1 NOx adsorber catalyst, also known as a lean NOx trap or NOx storage catalyst, using upstream and downstream NOx sensors. During routine NOx regeneration events the PCM expects the downstream NOx level to fall well below the upstream level, confirming the trap is effectively storing and reducing oxides of nitrogen. P2000 is set when the PCM detects that the NOx adsorber on Bank 1 is no longer achieving the stored threshold of NOx conversion efficiency across a diagnostic monitor, indicating a degraded catalyst, a sensor p...

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