Cummins fault code 2387
VGT Actuator Driver Circuit (Motor): not responding / out of adjustment
What it means
Cummins' description: VGT Actuator Driver Circuit (Motor) - Mechanical system not responding or out of adjustment.
SPN 641 is Engine Variable Geometry Turbocharger Actuator #1. 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 turbocharger forces air into the engine. Most modern Cummins engines use a variable geometry turbo (VGT) with an electronic actuator. The ECM watches intake manifold pressure, turbo speed and compressor temperatures to control boost.
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 brief underboost code climbing a hill that clears, with normal power the rest of the time.
Schedule a repair
Noticeable power loss, black smoke, or amber lamp with a boost or VGT code. Get it checked. Boost leaks and sticky VGT actuators get worse and hurt fuel economy.
Stop and get help
Loud whine or grinding from the turbo, heavy smoke, oil pouring out of the exhaust, or a stop lamp. Shut it down. A failing turbo can feed parts or oil into the engine.
Common causes
The sensor reading itself is out of range or the condition is real, so look at the system:
- Boost leak: split charge air hose, loose clamp, cracked charge air cooler
- VGT vanes sticking from soot
- Worn or damaged turbo
- Clogged air filter or intake restriction
- Exhaust restriction from a plugged DPF
What you can check before calling
- Listen for a new hiss or whistle under load, a typical sign of a boost leak
- Check charge air hoses and clamps for oil or soot
- Check the air filter restriction indicator
- Notice whether power loss happens only under heavy load or on hills
Clearing the code without fixing the cause usually brings it right back, and on emissions systems it can restart derate timers.
Engines and sources
Listed by Cummins for: QSB 6.7, QSL 9, QSX 15, QSB 4.5. 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
- 1894 SPN 641 FMI 9
VGT Actuator Driver Circuit: abnormal update rate - 1898 SPN 641 FMI 13
VGT Actuator Controller: out of calibration - 1962 SPN 641 FMI 15
VGT Actuator Driver Over Temperature (Calculated): reading above normal (least severe) - 1976 SPN 641 FMI 15
VGT Actuator Driver Over Temperature (Calculated): reading above normal (least severe) - 2198 SPN 641 FMI 11
VGT Actuator Driver Circuit: root cause not known - 2449 SPN 641 FMI 13
VGT Actuator Controller: out of calibration - 2634 SPN 641 FMI 12
VGT Actuator Controller: bad device or component - 2635 SPN 641 FMI 31
VGT Actuator Driver Circuit: condition exists
Related Turbo, VGT and boost codes
- 2347 SPN 2629 FMI 15
Turbocharger Compressor Outlet Temperature (Calculated): reading above normal (least severe) - 2346 SPN 2789 FMI 15
Turbocharger Turbine Intake Temperature: reading above normal (least severe) - 2451 SPN 2789 FMI 16
Turbocharger Turbine Intake Temperature: reading above normal (moderately severe) - 2288 SPN 103 FMI 15
Turbocharger 1 Speed: reading above normal (least severe) - 2973 SPN 102 FMI 2
Intake Manifold 1 Pressure: erratic or intermittent signal - 3348 SPN 1176 FMI 1
Turbocharger 1 Compressor Intake Pressure: reading below normal (most severe)
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 2387 mean?
Cummins fault code 2387 is J1939 SPN 641 FMI 7: VGT Actuator Driver Circuit (Motor) - Mechanical system not responding or out of adjustment. In plain terms: vgt actuator driver circuit (motor): not responding / out of adjustment.
Can I keep driving with Cummins code 2387?
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 2387?
SPN 641 identifies the part or system (Engine Variable Geometry Turbocharger Actuator #1). FMI 7 describes the type of failure: not responding / out of adjustment.
What usually causes Cummins code 2387?
The most common causes are: boost leak: split charge air hose, loose clamp, cracked charge air cooler; vGT vanes sticking from soot; worn or damaged turbo.
Diesel down in the Midlands?
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