P2202 — NOx Sensor Circuit Low (Bank 1 Sensor 1)
NOx sensor circuit signal low (upstream).
P2202 is logged when the upstream NOx sensor reports a signal voltage below the ECU's expected range — typically meaning the sensor element has failed short, or there is a wiring or ground fault.
P2202 symptoms
- AdBlue / Check Engine warning
- Sister code P2200 commonly appears alongside
- AdBlue countdown
- Reduced power
Common causes of P2202
Sensor element failed short
Internal failure of the upstream NOx sensor.
Signal wire short to ground
Chafed loom near the manifold or transmission bellhousing.
Failed sensor heater
Sensor never reaches operating temperature.
Ground fault at ECU side
A poor chassis ground point can drag signal voltage low.
Vehicles affected by P2202
- • Mercedes Sprinter, Vito, C-Class
- • BMW X5, 5 Series, 3 Series
- • Audi A6, Q5, Q7
- • VW Crafter, Touareg
- • Ford Transit, Ranger
P2202 diagnostic process
- Read upstream NOx sensor live mV value
- Signal-wire continuity and short-to-ground test
- Sensor heater current draw test
- Inspect ECU and chassis grounds
Common P2202 repairs
- Replace upstream NOx sensor with OE-coded part
- Repair signal-wire short to ground
- Code new sensor and reset adaptations
- Clean and re-torque chassis ground points
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Google Reviews
5 / 5
Based on 293+ Google reviews for our sister business Fast Lane Performance — the same team behind Fastlane AdBlue Solutions.
Read all reviews on Google →P2202 FAQs
Yes — left unresolved, P2202 typically progresses from a dashboard warning to limp mode, then to the AdBlue 'no engine start in X miles' countdown. The ECU is designed to enforce emissions compliance, so it will not clear itself by driving. A specialist diagnosis is needed.