Multiple System Failure Plagues Buick, Diagnosis Help

Having dealt with a similar issue on my 2008 Buick LaCrosse, I can share my experience as someone with moderate expertise in car electronics. The symptoms match what happened to my car, multiple system failures and various fault codes appearing simultaneously. After several diagnostic attempts, it turned out the root cause was incorrect coding in the control module. The check engine light was flashing because the module was sending conflicting signals to different systems. The repair involved having the control module properly recoded and all fault codes reset. The total repair cost was 360 Euro, which included diagnostic time and the actual coding work. After the fix, all systems returned to normal operation and the error messages disappeared. To better assist with your specific case, could you share: Which specific fault codes are you getting from the OBD-II scanner? Did these issues start suddenly or gradually? Have you had any recent repairs or battery disconnections? Is the car still driveable, or are any critical systems affected? This information would help determine if your issue is similar to what I experienced or if there might be different underlying problems that need attention.

Last serviced at 157089 KM and after clearing the fault codes, similar symptoms returned within a few days. The diagnostic scanner showed more unusual codes this time. The car drives but feels sluggish and occasionally hesitates. The check engine light keeps coming back despite multiple resets. Already tried disconnecting the battery for 30 minutes but that only temporarily solved the issue. A professional engine diagnostics session might be needed since basic troubleshooting hasnt resolved these recurring problems. Looking for input on next steps before taking it to a specialist.

Based on what you described, your situation mirrors my experience exactly. After my initial coding fix on my Buick LaCrosse, the problems also returned within days, showing those same symptoms, sluggish performance, hesitation, and persistent check engine light activation despite multiple resets. When fault codes keep returning after being cleared, its typically a sign of a deeper issue with the control module rather than just corrupt data. In my case, the module itself had partially failed, not just its programming. Basic resets and code clearing provided only temporary relief, just like youre experiencing. The recurring malfunction indicator and multiple system errors pointed to a faulty main control module that needed replacement rather than just reprogramming. After replacing the module, all systems stabilized and the unusual fault codes stopped appearing. Before going to a specialist, try documenting: All fault codes that appear, When the check engine light reactivates, Which systems show errors and when, Any patterns in when the hesitation occurs This information will help the technician diagnose whether your control module needs replacement like mine did, or if theres another underlying cause triggering these cascading system failures.

Thanks for the detailed response regarding your LaCrosse repair experience. The multiple fault codes returning after reset is definitely concerning. I just downloaded and saved all the current engine diagnostics data from my OBD-II scanner to share with the specialist. Documentation is underway, started a log of when systems fail and which malfunction indicator lights appear. The hesitation seems most noticeable during initial acceleration and after the engine warms up. Going to book a professional diagnostic session next week. Based on the similar symptoms you described with your control module failure, I will make sure they thoroughly check that component. Really hoping its just a module issue and not something more complex affecting multiple systems. Will update the forum once I get a proper diagnosis and repair solution from the specialist. The information about your repair outcome is helpful for setting expectations about potential fixes.