U0549 code meaning
Invalid Data Received From Remote Accessory Module
What U0549 means
No manufacturer explains in public what the remote accessory module is; the term shows up only in code lists, together with its lost-communication partner U0248. Going by the name, it is a body-side unit controlling accessories away from the main controllers, and it is distinct from the accessory protocol interface module covered by U0554. GM's Saab 9-5 documentation describes the supervision behind such codes: receivers watch for expected signals, substitute defaults when a signal is not valid and set a code against the sender, and its code list splits invalid data into subtypes such as wrong message counter, checksum error or implausible value. U0549 follows that scheme for this module. What stops working depends on the vehicle; driving is not affected.
U0549 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U0549
- An accessory function controlled by this module does not work
- Code stored without noticeable effect
Common causes of U0549
- PossibleRemote accessory module internally faulty
- PossibleRetrofitted or upfitter equipment disturbing the module's data
- Less likelyLow battery voltage or power interruption while the module was active
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Remote accessory module
What each part of U0549 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 49 | The exact fault in that area. |
What to do next
- Note U0549 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 U0549
What does U0549 mean?
U0549 means "Invalid Data Received From Remote Accessory Module". No manufacturer explains in public what the remote accessory module is; the term shows up only in code lists, together with its lost-communication partner U0248. It is a generic code, so it means the same on every make.
Is it safe to drive with U0549?
U0549 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will U0549 fail an emissions test?
U0549 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 U0549 to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will U0549 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.