U0204 code meaning
Lost Communication With Door Control Module F
What U0204 means
U0204 is set when door control module F stops answering. On the 2011 Saab 9-4x, whose U-code list comes from GM, the letter F belongs to the right rear door switch panel, the mirror-image partner of U0203 on the left. Before any repair, GM preliminary information PIC5741A (2013 Cadillac ATS, 2010–2013 SRX) is worth knowing: U0204, together with a long series of other communication codes and an instrument self-test, may appear only because the scan tool plug sits loosely in a diagnostic socket with spread terminals, most often ground pins 4 and 5. Checking and replacing those terminals comes first. With a genuine dropout, the window and lock switches at the right rear stop responding. No MIL is set.
U0204 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyMedium, DIY possible
- Typical labor0.3 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U0204
- Right rear window or lock switches inoperative
- Codes appear together with an instrument self-test when the scan tool is plugged in
Common causes of U0204
- Most likelySpread terminals in the diagnostic connector, false entries while testing (GM)
- PossibleBroken wires in the right rear door hinge harness
- PossibleLoose or corroded door connector pins
- Less likelyRear door switch panel module faulty
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Door module fCAN bus
What each part of U0204 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 04 | The exact fault in that area. |
What to do next
- Note U0204 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 U0204
What does U0204 mean?
U0204 means "Lost Communication With Door Control Module F". U0204 is set when door control module F stops answering. It is a generic code, so it means the same on every make.
Is it safe to drive with U0204?
U0204 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will U0204 fail an emissions test?
U0204 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 U0204 to fix?
Difficulty: medium. A typical repair takes 0.3 to 3 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will U0204 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.