Lost Communication With Reductant Pressure Sensor

Where it lives

For U0666, the part to look at first is the sensor named here.

Check these first

• The bus loses the reductant pressure sensor signal
• A clogged or crystallized DEF pressure port
• An open signal circuit at the reductant pressure sensor
• A corroded connector from DEF exposure
• A failed reductant pressure sensor element

What to do next

1. Read reductant pressure on a scan tool
2. Inspect the sensor port for DEF crystals
3. Inspect the sensor connector and wiring
4. Check the signal and ground circuits
5. Replace the reductant pressure sensor if it stays offline
6. Clear the code and retest

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