What it means
The fuel additive control module — typical for diesel cars with a separate Eolys/Cerine additive tank that aids DPF regeneration — has requested the ECM to illuminate the MIL because of an emissions-relevant fault on its side. The original fault is in the additive module itself.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
On diesel vehicles with a fuel additive system, the additive control module manages the additive used to help the diesel particulate filter regenerate. This code means that module has asked the engine control module to turn on the malfunction indicator lamp because it has detected an emissions-related fault. The underlying problem is reported by the additive module, so this code alone does not identify the failed part.
Common causes
Most likely first.
- Internal fuel additive control module fault
- Wiring or connector fault
- Communication fault between the additive module and engine control module
Symptoms
- Check-engine light on
- Diesel particulate filter or emissions warning may appear
- Reduced engine performance or more frequent DPF regeneration may occur
How to diagnose it
- Read all stored and pending codes, including additive-module codes, and record freeze-frame data before clearing anything.
- Use a compatible scan tool to check the additive module's reported fault, status, and communication with the engine control module.
- Inspect the additive module connectors and wiring for corrosion, loose pins, damage, or poor grounds.
- Check the vehicle's communication network and module power supply if the additive module does not respond or reports a communication fault.
- Follow the manufacturer's diagnostic steps for the additive module's reported fault before replacing any module.
Common fixes
- Repair a loose, corroded, or damaged module connector.
- Repair damaged wiring, power, ground, or network connections.
- Address the additive-system fault identified by the module.
- Replace a confirmed faulty additive control module and configure it as specified by the manufacturer.
Can I keep driving?
If the vehicle runs normally, a short trip for diagnosis is usually reasonable, but avoid ignoring the warning or making repeated short journeys that interrupt DPF regeneration. Continued operation with an unresolved additive-system fault can lead to failed or more frequent regeneration and emissions-system damage.
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.