Cummins fault code 2878
Fuel Drain Valve: not responding / out of adjustment
What it means
Cummins' description: Aftertreatment Fuel Drain Valve - Mechanical system not responding or out of adjustment.
SPN 4097 is Aftertreatment 1 Fuel Drain Actuator. FMI 7 means the ECM commanded something to move or change and it didn't respond the way it should: sticking, binding, worn, or out of adjustment.
The DOC (diesel oxidation catalyst) sits ahead of the DPF and burns fuel and hydrocarbons to heat the exhaust for regeneration. Some engines have a separate aftertreatment fuel doser (the 7th injector) that sprays fuel into the exhaust for regen.
What the lamp means
An amber (yellow) warning lamp means the engine can usually keep running, but the fault should be repaired soon, ideally the same day.
Green, yellow, red: three ways this can look
The same code can be a quick fix or a reason to shut down. Match your situation to the closest example.
Keep an eye on it
A temperature sensor code that appears once and clears, with regens finishing normally.
Schedule a repair
Regens failing or taking much longer than usual, along with DOC or doser codes. Book diagnosis before the DPF loads up.
Stop and get help
Raw fuel smell, smoke out of the stack, or a stop lamp. Don't run it. Unburned fuel in the exhaust is a fire risk and can destroy the DPF.
Common causes
The sensor reading itself is out of range or the condition is real, so look at the system:
- Aftertreatment fuel injector clogged or coked up
- DOC face-plugged with soot or oil
- DOC catalyst worn out or contaminated
- Fuel or air leak at the doser assembly
- Exhaust leak ahead of the DOC
What you can check before calling
- Look for soot or fuel residue at the aftertreatment fuel doser and lines
- Check for exhaust leaks between the turbo and the DOC
- Note whether regens are completing or being interrupted
Clearing the code without fixing the cause usually brings it right back, and on emissions systems it can restart derate timers. For the bigger picture, read our guide: DPF regeneration explained: passive, active and forced.
Engines and sources
Listed by Cummins for: QSX 15, QSG 12. Cummins uses the same fault code numbers across its electronic engines, including on-highway models like the ISB/B6.7, ISL/L9 and ISX/X15, though not every code applies to every engine or software level. Source: Cummins Tier 4 Fault Codes. Always confirm with Cummins service information (QuickServe) for your engine serial number.
Same SPN, other failure types
Related DOC and aftertreatment fuel doser codes
- 2778 SPN 3481 FMI 16
Fuel Rate: reading above normal (moderately severe) - 2638 SPN 5298 FMI 17
DOC Conversion Efficiency: reading below normal (least severe) - 2637 SPN 5018 FMI 11
DOC Face Plugged: root cause not known - 3152 SPN 4809 FMI 3
Warm Up DOC Intake Temperature Sensor Circuit: circuit voltage high / shorted high - 3153 SPN 4809 FMI 4
Warm Up DOC Intake Temperature Sensor Circuit: circuit voltage low / shorted low - 3154 SPN 4809 FMI 2
Warm Up DOC Intake Temperature: erratic or intermittent signal
Look up another code
Cummins fault code (like 1922), J1939 SPN and FMI (like SPN 3251 FMI 0), or an OBD-II code (like P0420).
Questions
What does Cummins fault code 2878 mean?
Cummins fault code 2878 is J1939 SPN 4097 FMI 7: Aftertreatment Fuel Drain Valve - Mechanical system not responding or out of adjustment. In plain terms: fuel drain valve: not responding / out of adjustment.
Can I keep driving with Cummins code 2878?
Usually for a short time, if the engine runs normally and no other warnings are on. Get it diagnosed soon, because many amber codes lead to a derate if ignored. Look at the green, yellow and red examples on this page to judge your situation.
What is the SPN and FMI for Cummins code 2878?
SPN 4097 identifies the part or system (Aftertreatment 1 Fuel Drain Actuator). FMI 7 describes the type of failure: not responding / out of adjustment.
What usually causes Cummins code 2878?
The most common causes are: aftertreatment fuel injector clogged or coked up; dOC face-plugged with soot or oil; dOC catalyst worn out or contaminated.
Diesel down in the Midlands?
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