U0203 code meaning
Lost Communication With Door Control Module E
What U0203 means
U0203 reports a missing door control module E. For the 2011 Saab 9-5, GM fills this slot with the left rear door switch panel, so on these GM platforms E is the electronics behind the rear left window and lock switches rather than a fifth door. GM preliminary information PIT5606J (GMC Acadia and Cadillac XT5, 2017–2021) lists U0203 among a crowd of U-codes that show up together when the instrument panel harness rubs through at the steering column next to the intermediate shaft, or when water reaches the body control module through a blocked HVAC drain or enters connectors such as X200, X201 and X500. Door locks cycling while driving or seats moving by themselves belong to that picture. The code alone sets no MIL.
U0203 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor1 to 4 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U0203
- Left rear window or lock switches without function
- Door locks cycle on their own while driving
- Many other lost-communication codes stored at once
Common causes of U0203
- Most likelyInstrument panel harness chafed at the steering column (GM Acadia/XT5)
- Most likelyWater at the body control module or in body connectors
- PossibleBroken wires between rear door and body
- 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 eCAN bus
What each part of U0203 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 03 | The exact fault in that area. |
What to do next
- Note U0203 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 U0203
What does U0203 mean?
U0203 means "Lost Communication With Door Control Module E". U0203 reports a missing door control module E. It is a generic code, so it means the same on every make.
Is it safe to drive with U0203?
U0203 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will U0203 fail an emissions test?
U0203 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 U0203 to fix?
Difficulty: medium. A typical repair takes 1 to 4 hours of work. This is a job for a workshop.
Will U0203 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.