Let’s say you have an (rail pressure too low). Do not buy a pump yet.

Data from the Electronic Controlled Air Suspension (ECAS) system.

: It is usually found inside the chassis behind the diesel tank, protected by a black snap-on cover. Check for corroded pins or loose multi-plugs.

On most Stralis models, you can view active faults directly on the dashboard's display:

Disconnect all trailer electrical lines (7-pin, 15-pin, ABS/EBS). Clear the dashboard faults.

Turn off the main battery isolation switch (if equipped) or disconnect the negative battery terminals.

A yellow RFC light can also point to issues with the vehicle's air brake system, as the RFC monitors the pressure sensors on the air processing unit (APU).

Rear tail lights, brake lights, indicators, and reverse alarms.

Faulty device or component (The RFC module itself or the connected smart valve may be dead). Step-by-Step Troubleshooting Guide for RFC Faults

The RFC receives data from the height sensor that defies physical logic (e.g., voltage too high or too low). This indicates a snapped sensor linkage arm or a failed internal potentiometer in the sensor.

Turn the ignition to the position but do not start the engine.

: If the code relates to air pressure (RFC 09), inspect the Air Processing Unit (air dryer) located in the middle of the chassis .

: If you have a general RFC system fault combined with air issues, check the air pressure sensor on top of the air dryer unit in the middle of the chassis.

Internal coil failure in valve block or corroded connector pin. Axle Lift Solenoid Command circuit for tag/pusher axle lift failed. Corroded solenoid plug under the chassis. RFC 51 Trailer Power Line (24V) Short circuit or overload on trailer auxiliary power. Damaged suzie coil/curly cable or shorted trailer wiring. RFC BC CAN Bus Communication Loss of communication between RFC and Body Computer. Broken twisted-pair CAN wiring or corroded main frame plug. Understanding FMI (Failure Mode Identifiers)