U350D code meaning
Control Module Cooling Fan Circuit Low
What U350D means
U350D is set when the voltage or current feedback in a control module's fan circuit sits below the window the module expects. Usually the fan supply or control wire touches ground, or the motor itself has shorted turns, so the output stage limits current or switches off and the fan stands still; a blown fan fuse produces the same picture. Electronics with a dedicated fan exist, for example the charger of the 2021 Toyota RAV4 Prime with its fan speed sensor (T-SB-0021-21), and CARB demands that electrical outputs cooling inverters and batteries be checked for circuit faults. No manufacturer publishes U350D. Once warm, the module will most likely protect itself by lowering its output. An open circuit is U350C, a short to voltage U350E.
U350D at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.5 to 2.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U350D
- Module fan does not run
- Reduced function or shutdown of the module when hot
- Blown fan fuse
Common causes of U350D
- Most likelyFan supply or control wire chafed through to ground
- PossibleFan motor with shorted windings drawing excess current
- PossibleFan fuse blown as a result of the short
- Less likelyOutput stage in the module pulling the line low
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Module cooling fanFan wiring
What each part of U350D means
| U | Network system: communication between the control modules (CAN bus). |
| 3 | Reserved range, usually generic. |
| 0D | The exact fault in that area. |
What to do next
- Note U350D 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 U350D
What does U350D mean?
U350D means "Control Module Cooling Fan Circuit Low". U350D is set when the voltage or current feedback in a control module's fan circuit sits below the window the module expects. It is a generic code, so it means the same on every make.
Is it safe to drive with U350D?
Drive gently and only to a workshop. With U350D the car can go into limp mode (reduced power) to protect itself.
Will U350D fail an emissions test?
U350D is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is U350D to fix?
Difficulty: medium. A typical repair takes 0.5 to 2.5 hours of work. This is a job for a workshop.
Will U350D clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.