U040D code meaning
Invalid Data Received From Turbocharger/Supercharger Control Module A
Network system Generic code U04xx codes Check engine light
What U040D means
Turbocharger/supercharger control module A is in practice an electronic charger actuator that sets the vanes of a variable-geometry turbine or a wastegate on command and reports position and status back. U040D means those reports arrive but the engine controller judges them invalid. No manufacturer documents U040D publicly. The module is documented through its lost-contact code U010C: GM's 2017 small-diesel table expects its frames on a dedicated sensor bus, and FCA replaced the turbo actuator of 2015 Ram 2500/3500 trucks with the 6.7 L Cummins under a warranty extension when U010C came with boost codes (09-005-22). With invalid actuator data the boost loop cannot be closed with confidence, so the controller usually caps boost and torque; boost control is emission-relevant under CARB, so a MIL is likely. U040E is module B.
U040D at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor1 to 4 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U040D
- Check engine light
- Noticeably reduced power (limp mode)
- Boost pressure codes stored alongside
Common causes of U040D
- Most likelyElectronics of the turbo actuator degraded by heat
- PossibleSticking vanes or linkage making the actuator report implausible positions
- PossibleConnector or sensor bus line at the actuator damaged
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Boost control module a
What each part of U040D means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 0D | The exact fault in that area. |
What to do next
- Note U040D and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about U040D
What does U040D mean?
U040D means "Invalid Data Received From Turbocharger/Supercharger Control Module A". Turbocharger/supercharger control module A is in practice an electronic charger actuator that sets the vanes of a variable-geometry turbine or a wastegate on command and reports position and status back. It is a generic code, so it means the same on every make.
Is it safe to drive with U040D?
Drive gently and only to a workshop. With U040D the car can go into limp mode (reduced power) to protect itself.
Will U040D fail an emissions test?
Yes, it can. U040D is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is U040D to fix?
Difficulty: hard. A typical repair takes 1 to 4 hours of work. This is a job for a workshop.
Will U040D clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.