Reductant Level Sensor C Circuit Intermittent/Erratic

Where it lives

For P21B1, the circuit described runs through the sensor. The description of P21B1 reports a fault at the sensor.

Check these first

• A failed sensing element inside reductant level sensor C
• An intermittent fault in the sensor C wiring
• Corrosion or water in the sensor C connector
• Urea crystallization on sensor C
• An incorrect sensor C for the vehicle

What to do next

1. Read the reductant level sensor C value on a scan tool
2. Watch the sensor C signal for dropouts on a drive
3. Inspect the sensor C connector for corrosion or water
4. Clean the sensor C of urea crystallization
5. Replace the reductant level sensor C if the signal is erratic
6. Clear the code and retest

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