P2202
ModerateP2202 — NOx Sensor Circuit Low Input, Bank 1
Description
What the Code Means
Code P2202 indicates a low signal level from the NOx sensor located in Bank 1 (cylinder side 1–3). The NOx sensor measures nitrogen oxide concentration in the exhaust and sends data to the DME for selective catalytic reduction (SCR) control. A low signal can be caused by an open wire, a short to ground, or a faulty sensor. This fault appears on BMW and Mercedes-Benz vehicles.
Symptoms
Symptoms
- Engine: reduced fuel economy, possible black smoke from the exhaust
- Indicators: Check Engine light comes on
- Conditions: symptoms may appear under any load, especially during active SCR operation
Causes and fixes
Diagnosis and Repair
Step 1: Check the Electrical Circuit
- Using a multimeter, check the Bank 1 NOx sensor circuit for an open and a short to ground.
- Inspect the connectors for corrosion or damage.
Step 2: Replace the Sensor
- If the circuit is intact, replace the Bank 1 NOx sensor.
- Use an original BMW sensor or a quality equivalent.
- After replacement, reset the adaptations through ISTA or INPA.
Possible secondary damage
Secondary Problems
Ignoring the fault can lead to improper SCR (urea injection) operation, which will cause increased NOx emissions and possible catalytic converter clogging. Long term, this may require costly repair of the entire exhaust aftertreatment system.