What does this code mean?
The wording below belongs to the named make and communication. Match the complete code, reporting module, model year and engine before applying it.
A code identifies a detected condition, not a part that must automatically be replaced.
Manufacturer communications
2Original wording in English
MACK
Reported code forms P0401-00
Diagnostic / Troubleshooting Procedures For EGR System Components; Diagnostic Trouble Codes (DTC) P0401-00, P0402-00, P04DD-00, P1121-00, P1121-98 Or SPN 2659 FMI 16, SPN 2659 FMI 18, SPN 412 FMI 0, SPN 412 FMI 15 -…
MACK
Reported code forms P0401
EGR MASS FLOW RATE LOW. THIS BULLETIN IS RELEASED TO ADDRESS HIGH COUNTS OF DIAGNOSTIC TROUBLE CODE (DTC) SPN 2659 FMI 18 OR P0401 ONLY DURING NORMAL TO HIGH LOAD DRIVING CONDITIONS ON VEHICLES ASSEMBLED BETWEEN JANUARY…
Check vehicle applicability
5A listed vehicle is a research lead. Confirm the engine, production range and software in the manufacturer's information.
Before replacing a part
Record codes and freeze-frame data. Check battery condition, related codes and visible wiring or hose damage. Follow the vehicle's diagnostic procedure and test results before replacing parts.
Can I keep driving?
A code alone cannot establish whether driving is safe. A flashing malfunction light, severe shaking, overheating, oil-pressure warning or loss of braking or steering needs prompt attention. Stop in a safe place and seek assistance when control or engine safety is affected. Follow the vehicle handbook.