P0401: Abgasrückführung (AGR) — Durchsatz zu gering
Abgasrückführung (AGR) — Durchsatz zu gering: Manifold pressure or temperature change when EGR is commanded open is below expected threshold.
| Trouble Code (DTC) | P0401 |
|---|---|
| Official SAE Definition | Abgasrückführung (AGR) — Durchsatz zu gering |
| Vehicle Subsystem | powertrain |
| Driving Severity | MEDIUM |
Observable Symptoms
- Check Engine Light on
- Pre-ignition ping/knock under light throttle
- Elevated NOx emissions
Most Probable Root Causes
- Carbon soot build-up blocking EGR passages or pintle valve
- Faulty EGR vacuum solenoid or position sensor
- Plugged DPFE / differential pressure tube
Step-by-Step Diagnostic Procedure
- Inspect and clean carbon deposits from EGR valve and intake manifold ports
- Command EGR open with scan tool at idle and verify engine RPM drops or stumbles