U025ALost Communication With Special Purpose Vehicle Control Module B
- Generic OBD-II code · Network
- How the car detects it
- U025A concerns the second slot for special purpose controllers. No manufacturer documents this code publicly. Why more than one slot exists becomes clear from an Audi patent: it describes a configurable control module for police cars, fire engines, taxis or vehicles for disabled occupants, linked through CAN, LIN or other interfaces, that turns a standard car into a commercial vehicle by adding function units. A conversion may thus carry several such boxes, for example one for the light bar and one for a tail lift. GM's 2024 Universal Vehicle Module shows the typical layout of one such unit. A listening module sets U025A when frames from unit B stop; which module listens and how long it waits is not published. Start at the body builder's wiring and fuses. Driving is normally not affected; U055B covers corrupt data.
- What you may notice
- Functions of the second conversion unit inoperative
- Warning or message from the conversion control panel
- Likely causes
- LikelySecond add-on unit unpowered, often via a switched or separately fused upfit circuit
- PossibleFaulty splice or connector where the conversion joins the vehicle bus
- PossibleUnit removed or replaced while the vehicle still expects it
- RareInternal failure of controller B
- Repair
- Medium · Usually a job for a workshop.Typical cost: €50 – €700
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.