P0400
System
Powertrain (Emissions)
Scanner som krävs
Enhanced OBD2 scanner (live data graphs, freeze frame, battery voltage test)

Exhaust Gas Recirculation Flow Malfunction

Understand P0400, common causes, and the right FOXWELL scanner to diagnose it.

General EGR system fault — flow detected when none expected or control circuit issue.

Vanliga symptom

  • Rough idle
  • Knock under acceleration
  • Check engine light

Typiska orsaker

  • Failed EGR valve
  • Carbon blockage
  • Vacuum supply to EGR solenoid
  • DPFE/MAP sensor on Ford EGR

Vilken scanner behöver du?

Enhanced OBD2 scanner (live data graphs, freeze frame, battery voltage test)

Använd live-data och freeze frame innan du byter delar. ABS-, SRS- och U-koder kräver oftast en fullsystems-scanner.

Diagnostiktips

  • Spara freeze frame när koden först sätts
  • Rensa koden först efter att orsaken är åtgärdad
  • Kontrollera relaterade väntande koder
  • Verifiera batterispänning över 12,4 V innan du misstänker sensorer

Rekommenderade FOXWELL-scannrar

Vanliga frågor

Can I diagnose P0400 with a basic code reader?
P0400 may set in the engine module, but related diagnostics often benefit from an enhanced or full-system scanner with live data and freeze frame.
Is it safe to drive with P0400?
It depends on the code and symptoms. Flashing check engine lights and misfire codes should be addressed immediately. Consult a professional if unsure.