P2202: NOx Sensor Circuit Low Bank 1 Sensor 1
What to do
The car will drive normally and the inducement countdown described under P2200 still applies. A reading of almost no NOx is not good news — it means the sensor has stopped reporting rather than that emissions are perfect. Ask for the wiring and connector to be checked before the sensor is replaced.
What this code means
The NOx sensor is reporting a value below its valid range — either a genuine electrical low, or a reported concentration so low the module treats it as impossible.
The second of those is worth pausing on, because an implausibly low NOx reading is counterintuitive: it looks like good news. It is not. A diesel under load produces oxides of nitrogen as an inevitable product of hot lean combustion, so a sensor reporting almost none is far more likely to have stopped sensing than to be witnessing a miracle of combustion. Sensors that have been contaminated or have lost their heater commonly settle at the bottom of their range rather than going open circuit.
The electrical explanations are the usual ones, with the usual caveat about where these parts live: the sensor and its connector sit under the vehicle, in the path of everything the road throws up.
Likely causes
Start here
- Wiring shorted to ground · moderate
- Faulty NOx sensor · moderate
- Corroded or loose connector · easy
Less common
- Contaminated NOx sensor element · moderate
- Damaged wiring harness · moderate
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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