What it means
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.
How it works
In diesel vehicles fitted with a fuel additive tank, the additive control module tracks the additive used to help the DPF regenerate. This code records the module's request for the additive warning lamp, usually because the additive has reached its service threshold. If the supply is not restored when required, the system may eventually be unable to support DPF regeneration.
Common causes
Most likely first.
- Fuel additive level low or at its service threshold
- Faulty additive-level sensor
- Wiring or connector fault
Symptoms
- Fuel additive or service warning light on
- DPF warning may appear
- More frequent or unsuccessful DPF regeneration may occur
How to diagnose it
- Read the additive-module data and any related codes to confirm the warning request and the module's reported additive level or service status.
- Check the vehicle's service history for a recent additive refill or reset, since an unrecorded refill can leave the warning active.
- Inspect the additive tank, level sensor, connectors, and nearby wiring for damage, leaks, corrosion, or loose connections.
- Compare the reported level or sensor status with the manufacturer's diagnostic information to distinguish a low supply from a sensor or circuit fault.
- After servicing the additive supply or sensor, verify that the module recognizes the corrected level using the specified service procedure.
Common fixes
- Refill the correct fuel additive using the manufacturer's procedure.
- Repair a loose or corroded level-sensor connector.
- Repair damaged wiring to the additive-level sensor.
- Replace a confirmed faulty level sensor and perform any required reset.
Can I keep driving?
Arrange the additive service promptly and follow any DPF warnings; avoid putting it off or repeatedly interrupting regeneration. Driving with the tank below its service threshold can eventually prevent effective DPF regeneration and lead to filter restriction.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.