Two problems related to engine and engine cooling have been reported for the 2003 Mercury Grand Marquis. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2003 Mercury Grand Marquis based on all problems reported for the 2003 Grand Marquis.
The contact owns a 2003 Mercury Grand Marquis. The contact stated while driving approximately 70 mph, the vehicle started losing motive power. The contact stated that the vehicle had shifted to limp mode and was almost side swiped by a tractor trailer. The contact stated that the check engine warning light was illuminated. The contact had not taken the vehicle to a local dealer. The vehicle had been towed to an independent mechanic; however, the vehicle was not diagnosed or repaired. The contact stated that the failure was intermittent at first but became a recurring failure. The manufacturer had not been informed of the failure. The failure mileage was approximately 240,000.
I started Mercury with foot on break like normal. Shifted into reverse. Car accelerated backwards at full speed. Brakes did not stop car. Attempted to shift into neutral but went into drive instead. Car accelerated forward at full speed with my foot still on break. Car hit metal post and tree knocking them down and dragging the tree 50 to 60 feet before stopping with my foot still on the break. Car had stopped accelerating. I turned off the ignition. This unintended acceleration had happened before. Two different dealers attempted to fix the problem. Both of them thought they had been successful but it happened again. Previously, applying the brakes stopped the car, but not this time. Someone could have been injured severely or killed.