U0274 code meaning
Lost Communication With Lighting Driver Control Module B
What U0274 means
U0274 is stored when the second lighting driver control module stops answering on its network. Lincoln documents a B unit on the 2025 Navigator, listed as LDCMB and updated with the same release 25.10.08 as its three siblings, but gives no position for it. What a silent driver does on its own is shown by TI's TPS92520-Q1 LED driver: a communication watchdog, set to about 1.67 s by default, switches the chip to limp-home current from preset registers when commands stop arriving. The lamp therefore often stays lit at a fixed level although the controller has lost the module. No manufacturer documents U0274 publicly. U0575 covers implausible data from the same unit.
U0274 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.3 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U0274
- Lamp stays at one fixed brightness and ignores dimming
- Lighting fault message
- Adaptive light functions switched off
Common causes of U0274
- Most likelyBus wire or connector to driver module B open or corroded
- PossibleSupply or ground of driver module B missing
- PossibleDriver module B software not current after an update
- Less likelyDriver module B internally faulty
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Lighting driver module bVehicle bus wiring
What each part of U0274 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 74 | The exact fault in that area. |
What to do next
- Note U0274 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 U0274
What does U0274 mean?
U0274 means "Lost Communication With Lighting Driver Control Module B". U0274 is stored when the second lighting driver control module stops answering on its network. It is a generic code, so it means the same on every make.
Is it safe to drive with U0274?
U0274 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will U0274 fail an emissions test?
U0274 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 U0274 to fix?
Difficulty: medium. A typical repair takes 0.3 to 3 hours of work. This is a job for a workshop.
Will U0274 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.