U0109 on Buick: How to Diagnose & Fix
Lost Communication With Fuel Pump Control Module "A"
1 Buick model · 1 documented issue · 1 critical · $500-$1,400 repair
U0109 on Buick by model: symptoms, diagnosis and fix
Second-generation Envisions have a repeating NHTSA pattern of the fuel pump control module failing, producing an engine that dies without warning while driving and a crank-no-start afterward, or that only fires on 7-8 of every 10 attempts. Owners report no warning lights and no stored codes in several cases. One especially dangerous report describes the vehicle stalling in a center freeway lane where the electronic shifter would not allow neutral with the engine off, stranding the car in traffic. Failures are documented from about 11,000 miles, and replacement modules have been back-ordered for extended periods.
Common Symptoms
- Engine dies while driving with no warning
- Cranks but will not start, intermittently
- No check engine light or stored trouble codes at the time of failure
- Vehicle stalls and cannot be shifted to neutral to be pushed
How to Fix
Check fuel pressure and fuel pump power/enable at the module before replacing the pump assembly. The repair is replacement of the fuel pump control module (typically mounted at the rear of the vehicle) followed by module programming. Check GM's open recall and field-action list against your VIN, and verify the vehicle's shift-to-neutral procedure with the engine off so you can move it if it strands you.
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Sources for this issue (2)
U0109 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 U0109 mean on a Buick?
U0109 stands for "Lost Communication With Fuel Pump Control Module "A"." Sets when a module loses data-bus communication with the Fuel Pump Control Module 'A', which regulates electric fuel pump operation/pressure. Loss of these messages can interrupt fuel delivery. On Buick it is documented across 1 model: Envision.
What are the most common causes of U0109?
The most common causes of U0109 are: Open, shorted, or chafed bus wiring to the fuel pump control module, Corroded or loose module connector / poor ground, Blown fuse / lost power feed, Low battery voltage, Failed fuel pump control module. The specific cause varies by vehicle.
How much does it cost to fix U0109 on a Buick?
Published repair estimates on Buick range from $500 to $1,400 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for U0109 on a different make?
View U0109 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.