Diagnostic article Generic OBD-II
P2203: engine-out NOx raw value exceeds the sensor range
P2203 checks for a raw engine-out NOx reading above 2,990 ppm under valid sensing and air-control conditions.
Read before applying this article
Documented application
Documented 2025 GM diagnostic parameter monitor in 25OBDG04B.pdf; model, engine and calibration applicability require vehicle-specific confirmation.
The code alone does not identify a failed part or establish that a vehicle is safe to drive. Confirm the vehicle, reporting module and applicable service procedure.
P2203 is the high-range code for bank 1 NOx sensor 1 in the reviewed GM monitor. The direct criterion is a raw NOx concentration above 2,990 ppm. Despite the dictionary's circuit-high wording, this page does not define a voltage at an external signal pin.
Range validity comes before emissions interpretation
The check requires the sensor's current-control and electrical fault states to be clear. Lost communication and invalid CAN data must also be absent. P2203 therefore assesses an excessive reported concentration only after those supporting checks permit it.
A raw value beyond the monitored range should not automatically be used to diagnose a failed SCR catalyst. The sensor here is identified as engine-out, and this row addresses the validity of its high reading rather than downstream conversion efficiency.
An eligible high-range test
Relay voltage must exceed 11 volts, sensor supply exceed 9.90 volts and the NOx bus relay be commanded on. Dewpoint must be reached, the engine running, the combustion-mode enable flag satisfied and air-system control active. Failure qualification is 200 out of 240 samples on a 25-millisecond task, with Type B reporting across two trips.
Verification needs the raw signal and completed range test under those conditions. A lower value during an inhibited or uninitialized period does not establish recovery. The source provides no cause ranking, electrical pinout or replacement instruction. Exact vehicle and sensor applicability must be confirmed before using these calibration-specific limits.
Source: GM monitor, PDF page 1409.
Article source documents
Source checks describe how the text was prepared; they do not certify a diagnosis or confirm compatibility with every vehicle using this code.
Original code reference
Dictionary definition
NOx Sensor Circuit High Bank 1 Sensor 1
This definition retains its original catalog scope. The article above is limited to its explicitly documented application.
Reference scope
Generic OBD-II definition.
A manufacturer label does not establish the model, year, engine or module to which a diagnosis applies. Read the safety and diagnostic limits.
Definition source
- DTC Database: pinned community code definitions
Source checked · MIT