U0242 on Buick
Lost Communication With Headlamp Control Module "B"
U0242 on Buick vehicles indicates lost communication with headlamp control module "b". Au7o has documented this code across 1 Buick model — most commonly on LaCrosse. A controller is no longer receiving the periodic data-bus messages expected from Headlamp Control Module B (the opposite-side or secondary headlamp controller). Set after a calibrated timeout, it indicates lost communication with that lighting module.
Common Causes of U0242
- •Power/ground loss to the headlamp control module
- •Open/shorted bus wiring
- •Corroded/loose connectors
- •Failed headlamp control module/ballast driver
- •Network fault
U0242 on Buick by Model
Buick LaCrosse(1 issue)
- Headlamp Driver Module Overheats and Kills Headlights (Recall 15V519000)2005-2009
GM recalled the Buick LaCrosse under NHTSA campaign 15V519000 (GM number 14291) because the headlamp driver module (HDM) can overheat and fail. When the module fails, the headlamps and the daytime running lights stop illuminating. NHTSA notes that headlamps which do not come on reduce how well the driver can see the road ahead and how easily oncoming traffic can see the LaCrosse, raising the risk of a crash. The campaign as a whole covers roughly 429,170 vehicles across several GM, Isuzu and Saab models — that figure is campaign-wide and is not a count of LaCrosse sedans.
Looking for U0242 on a different make?
View U0242 across all makes →Frequently Asked Questions
What does U0242 mean on Buick?▼
U0242 stands for "Lost Communication With Headlamp Control Module "B"." A controller is no longer receiving the periodic data-bus messages expected from Headlamp Control Module B (the opposite-side or secondary headlamp controller). Set after a calibrated timeout, it indicates lost communication with that lighting module. On Buick specifically, this code is documented across 1 model.
What causes U0242 on Buick vehicles?▼
Common causes on Buick: Power/ground loss to the headlamp control module, Open/shorted bus wiring, Corroded/loose connectors, Failed headlamp control module/ballast driver, Network fault. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix U0242 on a Buick?▼
Repair costs vary widely depending on the root cause and specific Buick model.
Which Buick models have U0242 documented?▼
Au7o has documented U0242 on 1 Buick model: LaCrosse.