U0278 code meaning
Lost Communication With Seat Control Module L
What U0278 means
Seat control module L is the right-hand partner of K. On the 2025 Lincoln Navigator, Ford's SCML runs the second-row power seat on the passenger side; release SCML-25.5.5.3 targeted its memory function, and SSM 54226 lists it as the rear right-hand power seat module, with its own configuration app that must be run after a module change, for example when the seat ignores its fore-aft switch. U0278 signals that SCML has dropped off the network entirely, which no public bulletin covers for this code. Under-seat harnesses on sliding second-row seats are flexed with every adjustment, so connectors and wiring there deserve the first look. Only the right second-row seat loses its electrical functions.
U0278 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.3 to 2.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U0278
- Right second-row power seat inoperative
- Seat memory on that seat not working
Common causes of U0278
- Most likelyHarness under the sliding seat damaged by seat movement
- PossibleSCML configuration missing after replacement or update
- PossiblePower or ground to SCML interrupted
- Less likelySeat control module L internally faulty
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Seat control module lVehicle bus wiring
What each part of U0278 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 78 | The exact fault in that area. |
What to do next
- Note U0278 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 U0278
What does U0278 mean?
U0278 means "Lost Communication With Seat Control Module L". Seat control module L is the right-hand partner of K. It is a generic code, so it means the same on every make.
Is it safe to drive with U0278?
U0278 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will U0278 fail an emissions test?
U0278 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 U0278 to fix?
Difficulty: medium. A typical repair takes 0.3 to 2.5 hours of work. This is a job for a workshop.
Will U0278 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.