P2200Powertrain
Powertrain · SAE
NOx Sensor Bank 1 — Circuit
Meaning
The ECU has detected a fault in the circuit of the NOx sensor on bank 1 (upstream position, before the SCR catalyst). The sensor, which measures the nitrogen oxide concentration in the exhaust gases before treatment, is not providing a valid signal.
Common causes
- Damaged, loose, or oxidised connector or wiring on the NOx sensor B1
- Internally failed NOx sensor B1
- Missing supply voltage or ground at the sensor
- NOx sensor deteriorated by thermal damage or AdBlue crystal contamination
- Short circuit or open circuit in the sensor communication line (sensor CAN-bus)
Symptoms
- Check engine light on
- Upstream NOx data absent or fixed on scan tool
- ECU unable to calculate correct AdBlue dosing for the SCR system
- Possible power reduction or emission emergency strategy activation
- Related SCR/EGR codes possible
Severity
Moderate to high: without upstream NOx data the SCR system cannot dose AdBlue correctly, causing NOx limit exceedances and possible driving restrictions.
What to do
- Inspect the NOx sensor B1 connector and wiring for damage or oxidation
- Check supply voltage and ground at the sensor
- Verify sensor communication on the CAN network using a scan tool
- Measure sensor internal resistance; replace if out of specification
- Replace the sensor if electrically intact but not communicating