U0242 on 2005-2009 Buick LaCrosse — Lost Communication With Headlamp Control Module "B"
1 vehicles · 1 makes
How to diagnose and fix U0242: most-reported vehicles
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Buick LaCrosse · 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.
Common Symptoms
- Headlamps do not illuminate
- Daytime running lights do not illuminate
- Loss of forward lighting at night
How to Fix
The repair is free. GM notified owners and dealers replace the headlamp driver module at no charge; the recall repair began May 17, 2016. Buick customer service can be reached at 1-800-521-7300, and GM's internal recall number is 14291. Enter your VIN at nhtsa.gov/recalls to confirm whether your LaCrosse is included and whether the HDM replacement was ever performed.
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Sources for this issue (1)
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U0242 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does U0242 mean?
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.
What are the most common causes of U0242?
The most common causes of U0242 are: Power/ground loss to the headlamp control module, Open/shorted bus wiring, Corroded/loose connectors, Failed headlamp control module/ballast driver, Network fault. The specific cause varies by vehicle.
How much does it cost to fix U0242?
Repair costs vary widely depending on the root cause and vehicle.
Which vehicles are affected by U0242?
Au7o has documented U0242 across 1 vehicle models from 1 manufacturers: Buick.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.