P2585
Fuel Additive Control Module Warning Lamp Request
The fuel additive control module asks for the additive-low warning lamp to be illuminated — the additive tank (Eolys/Cerine, used to lower DPF regen temperature) is approaching empty or has reached a service threshold. Continued driving without refilling will eventually disable DPF regeneration.
- Check engine light: Not always
- Emissions related: No
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- Additive tank low — service refill requiredCommon
Parts involved
- Fuel Additive Tank
P2585 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.