After a Battery Swap. This 2009 ML350 Won’t Even Talk to Its Computer

A 2009 Mercedes ML350 that had been sitting idle for three months recently became a diagnostic puzzle for its owner. After multiple jump-starts got the SUV running, only for it to stall minutes later with a dashboard full of warning lights, the owner swapped in a fresh battery and cleared the codes.

For a couple of days, things seemed normal. Then the check engine light returned, and the real trouble began.

The codes that popped up, 1337, 0443, 0447, 0450, 0454, and 0228, point to a mix of evaporative emissions and fuel system issues. But the real scare came during a drive: the car suddenly lost power and refused to accelerate, forcing the driver to pull over. Clearing the codes got it home, but the check engine light came back the instant the ignition was turned on again.

Now the scanner can’t even find the engine control module (ECM) or the transmission control module, and the SUV won’t start at all.

Given that the ML350 had been running flawlessly for years with no water intrusion or obvious damage, a failed ECU is a strong suspect. But other possibilities include a bad battery connection, a failing alternator that’s sending erratic voltage, or even a corroded ground strap that’s disrupting communication between modules.

The owner is considering pulling the ECU for testing at a local shop in South Florida and is looking for recommendations on reliable repair or reprogramming services.