U0252 code meaning
Lost Communication With Lighting Control Module - Rear B
What U0252 means
Module B for rear lighting is the second unit driving lamps at the back end, and in practice it is often the trailer electronics. GM's code list for the 2011 Saab 9-5 assigns U0252 to the trailer interface control module. Ford does the same: on 2021-2023 F-150, 2022-2024 F-150 Lightning, Expedition, Navigator and the 2024 Ranger, the body control module, cluster or steering module records U0252, often with U0137, when the trailer module (TRM) drops off CAN; a five-minute power-down and new TRM software cured it (SSM 53236). Super Duty trucks of 2023-2025 showed the same pair when ground point G201 was not torqued correctly (SSM 53980), and a BCM self-test may leave a harmless U0252:87 history entry (SSM 51578). Trailer lamps or trailer brake messages fail; no MIL.
U0252 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.3 to 2 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U0252
- Trailer brake module fault or trailer warning in the cluster
- Trailer lamps or rear lighting functions inoperative
- Further U codes such as U0137 in body control module, cluster or steering module
Common causes of U0252
- Most likelyTrailer or rear lighting module stuck off the bus, software needs reset or update (Ford TRM)
- PossibleLoose or badly tightened body ground shared with the module (Ford G201)
- PossibleDamaged or corroded harness and connectors at the rear or tow bar area
- Less likelyStored history entry from a module self-test without a real fault
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Rear lighting module bVehicle bus wiring
What each part of U0252 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 52 | The exact fault in that area. |
What to do next
- Note U0252 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 U0252
What does U0252 mean?
U0252 means "Lost Communication With Lighting Control Module - Rear B". Module B for rear lighting is the second unit driving lamps at the back end, and in practice it is often the trailer electronics. It is a generic code, so it means the same on every make.
Is it safe to drive with U0252?
U0252 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will U0252 fail an emissions test?
U0252 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 U0252 to fix?
Difficulty: medium. A typical repair takes 0.3 to 2 hours of work. This is a job for a workshop.
Will U0252 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.