A track day at Atlanta Motorsports Park turned into a troubleshooting nightmare when my 2008 BMW suffered a catastrophic misfire. The engine felt like it was running on three cylinders, and the check engine light (CEL) flashed relentlessly. After limping the car into the driveway, it stalled completely. Restarting usually resolved similar past issues, but not this time.
The JB4 diagnostic tool revealed a 30BA fault code: injection misfire cylinders 1, 2, and 3, indicating a potential DME (Digital Motor Electronics) diode failure. Attempts to clear the code were unsuccessful. The car, now three and a half hours away from home, sits with its DME removed.
Research suggests this issue might be covered under the 8-year/80,000-mile federal emissions warranty. However, anecdotal evidence online points to dealerships often denying coverage. Fortunately, working at a European auto shop offers the possibility of attempting a DME diode repair.
A blown fuse in the DME compartment could also be the culprit, a possibility I unfortunately overlooked at the track. Checking this will be the first step next weekend. If the fuse isn’t the issue, a diode repair will be attempted. If that fails, contacting Autologic for coding a used DME to the car will be the next course of action.
While there’s a Technical Service Bulletin (TSB) for this issue on BMWs built between June 2007 and August 2007, my car, with a November 2006 build date, falls outside that range. Electronic components can fail, but the apparent prevalence of DME diode failures in these models raises questions.
