P3850moderate severityPowertrain
DPF Differential Pressure Sensor Rationality Error
on 2010 Audi A3 2.0L TDI I4 · FWD
What this code means
The DPF differential pressure sensor readings do not correlate with expected values based on engine load, exhaust flow, and DPF soot loading model.
Symptoms
- Check Engine Light
- Incorrect regen intervals
- Unnecessary forced regenerations
- DPF may be over-cleaned or under-cleaned
- Fuel economy affected by incorrect regen timing
Common causes
- Differential pressure sensor drift
- Pressure sensor hoses kinked or blocked
- Moisture in pressure sensor lines
- Sensor calibration error
- Soot model and sensor disagreement
Diagnostic steps
- Compare DPF differential pressure to expected values
- Inspect pressure sensor hoses for kinks or soot blockage
- Blow out pressure sensor hoses
- Test sensor zero-point calibration
- Compare soot loading model to pressure readings
Repair notes
Replace differential pressure sensor or clean hose connections. Recalibrate DPF soot loading model after repair.
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