25C800

What Code 25C800 Means

Code 25C800 indicates that the pipe nipple (Rohrstutzen) between the pressure sensor and the diesel particulate filter (DPF) may be partially clogged. This causes a delayed pressure drop after the engine stops: when the sensor readings are compared, pressure has not yet reached atmospheric. The engine management system detects the mismatch and stores the code.

The fault sits in the DPF differential pressure check. The pressure sensor connects to the DPF via a pipe nipple; when the nipple clogs, the pressure change dynamics are distorted, which can cause errors in estimating filter load and, as a result, power limitation.

Symptoms

• Power loss: sharp drop in power, the car won't exceed 50 mph; the problem appears intermittently.
• Message on the center console multifunction display: “Gruppo motore; Proseguire a velocità moderata. Non è disponibile l'intera potenza del gruppo motore. Rivolgersi Centro Assistenza” (engine fault; drive at moderate speed; full engine power is not available; contact a service center).

Diagnosis and Repair

The source has no confirmed fix. It lists the actions taken that did not resolve the fault:

• Replaced the intake manifold pressure sensor with a new aftermarket unit.
• Ran the “sostituzione filtro particolato” (particulate filter replacement) adjustment through the diagnostic tester.

Check the pipe nipple (Rohrstutzen) between the pressure sensor and the DPF for clogging with a wire or bottle brush, as stated in the code description.