P2204
NOx Sensor Circuit Intermittent (Bank 1)
The bank 1 NOx sensor signal drops out intermittently. Typical cause is a marginal connector, harness chafing near hot exhaust components, or thermal-cycling solder joints inside the smart sensor.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Symptoms
- Check engine light or NOx warning on
- AdBlue/DEF level or quality warning
- Possible no-start countdown after ignore period
- Failed emissions inspection (NOx)
Common causes
Ordered by how often each turns out to be the cause.
- Connector intermittent contactCommon
- Harness chafed near exhaustPossible
- Connector with intermittent contact under vibrationLess likely
Parts involved
- NOX Sensor
- NOX Sensor Wiring
P2204 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.