U0129 on Chevrolet: How to Diagnose & Fix
Lost Communication With Brake System Control Module A
1 Chevrolet model · 1 documented issue · 1 critical
U0129 on Chevrolet by model: symptoms, diagnosis and fix
GM recalled 2020 C8 Corvettes after finding that sensor contamination inside the electronic brake boost (eBoost) module can interrupt communication within the braking system. The C8 uses an electronically boosted brake system rather than a conventional vacuum booster, so when the module drops out the driver loses power assist and must apply substantially higher pedal effort to stop the car. NHTSA identified the consequence as increased crash risk. Owner complaints filed against the 2020 car back this up in blunt terms, with one owner relaying another customer's report that his brakes did fail and it was difficult to stop. Notification and remedy for campaign 20V588000 began December 9, 2020.
Common Symptoms
- Brake warning lights illuminate on the cluster
- Hard brake pedal requiring much greater effort
- Reduced braking performance and longer stopping distances
- Loss of brake assist without warning
How to Fix
Verify your VIN against campaign 20V588000 at nhtsa.gov/recalls or through a Chevrolet dealer; the remedy is free replacement of the electronic brake boost module. If the brake warning light or a 'Service Brake Assist' style message appears while driving, treat it as an immediate loss-of-assist warning: the brakes will still stop the car mechanically but need far more pedal force and far more distance. Increase following distance dramatically, avoid highway speeds, and get the car to a dealer without delay. Do not clear the fault and continue driving on the assumption it is a sensor glitch — the recall exists because the interruption is intermittent and repeats.
Sources for this issue (2)
U0129 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 U0129 mean on a Chevrolet?
U0129 stands for "Lost Communication With Brake System Control Module A." Sets when a module loses data-bus communication with Brake System Control Module 'A' (typically the ABS / electronic brake control module) and no longer receives its expected messages. On Chevrolet it is documented across 1 model: Corvette.
What are the most common causes of U0129?
The most common causes of U0129 are: Open or shorted bus wiring to the brake system module, Corroded or loose connector / poor ground, Blown fuse / lost power feed, Low battery voltage, Failed brake system control module. The specific cause varies by vehicle.
How much does it cost to fix U0129 on a Chevrolet?
Repair costs vary widely with the root cause and Chevrolet model; each issue on this page carries its own estimate where one is published.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.