One problem related to loud engine noise has 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 that there was an abnormal noise coming from the engine and the check engine warning indicator illuminated. The vehicle was taken to an independent mechanic where it was diagnosed that the number two cylinder spark plug misfired and the head of the motor needed to be replaced. The vehicle was not repaired. The manufacturer was notified of the failure. The failure mileage was approximately 178,000.