U0142 code meaning
Lost Communication With Body Control Module B
What U0142 means
U0142 reports that a second body controller, labelled B, has stopped talking. No maker explains publicly which unit carries this letter; depending on the design it may be a rear body module, a power distribution box or a comfort unit next to the main BCM (U0140) and module A (U0141). The only manufacturer document found that mentions the code is Toyota's 2014 Prius plug-in pre-delivery sheet: the short pin is pulled for shipping to save the battery, so U0142, U0155 and U0100 are expected and simply erased once it is refitted. That makes clear how easily a dormant or unpowered module produces this code. GM's U0100-U02FF logic applies: listeners expect the module's periodic availability message at 9-16 V and log its absence. Invalid data from module B is U0443. Usually no MIL.
U0142 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 U0142
- Body functions handled by module B do not work
- Scan tool cannot reach module B
- Often only a stored code without noticeable fault
Common causes of U0142
- Most likelyModule B without power: fuse, transport short pin or relay missing
- PossibleFlat battery or battery disconnect leaves a history code
- PossibleDamaged bus wire or loose connector to module B
- Less likelyBody 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
Body control moduleCAN bus wiring
What each part of U0142 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 42 | The exact fault in that area. |
What to do next
- Note U0142 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 U0142
What does U0142 mean?
U0142 means "Lost Communication With Body Control Module B". U0142 reports that a second body controller, labelled B, has stopped talking. It is a generic code, so it means the same on every make.
Is it safe to drive with U0142?
U0142 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will U0142 fail an emissions test?
U0142 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 U0142 to fix?
Difficulty: medium. A typical repair takes 0.3 to 3 hours of work. This is a job for a workshop.
Will U0142 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.