P24D4EGR Cooler Coolant Pump Feedback Circuit
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- Where an electric auxiliary pump moves coolant through the EGR cooler, the pump usually reports back to the engine controller on a separate wire, for example with a speed or status signal. P24D4 is the general fault of that feedback circuit: the signal is missing or cannot be interpreted, while the narrower cases of a line stuck below or above its band are P24AC and P24AD. The drive side may be fine; faults in the control line are P24A7 to P24AA. No manufacturer documents P24D4 publicly. CARB requires the controller to check inputs from emission-related components for circuit faults and rationality. Pierburg describes EGR coolers as part of the coolant circuit. Without valid feedback the controller cannot prove the cooler is supplied and may cut back EGR to protect it.
- What you may notice
- Malfunction indicator lamp on
- EGR reduced, possibly higher NOx and changed engine noise
- Coolant temperature warnings if the pump really stops
- Likely causes
- LikelyOpen feedback wire or loose connector at the pump
- PossibleFailed pump electronics no longer sending a status signal
- PossibleBlown fuse or failed relay leaving the pump without power
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €100 – €700
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.