443 problems have been reported for the 2003 Mercury Grand Marquis. The following chart shows the 19 most common problems for 2003 Mercury Grand Marquis. The number one most common problem is related to the vehicle's exterior lighting with 207 problems. The second most common problem is related to the vehicle's electrical system (54 problems).
In our research we use the PPMY index to compare the reliability of vehicles. The PPMY index of a certain model is defined as the problems reported per thousand vehicles per Year. The total sales of the 2003 Mercury Grand Marquis in the United States are 105,711 units [1]. If the total number of problems reported by Mercury Grand Marquis owners in the last 22 years is 443, and the age of the vehicle is 22, the PPMY index can then be calculated as
PPMY Index = 443 / 105,711 / 22 * 1000 = 0.19.
For more information, refer to this page: A study of reliability comparison across Mercury Grand Marquis model year vehicles.
The following chart shows the number of problems reported during each of the service years since the debut of the 2003 Mercury Grand Marquis in 2003.
| Service Year | Number of Problems |
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| 2003 |
When making the decision between buying a new or used Mercury Grand Marquis, the following table can be used to compare the 2003 Mercury Grand Marquis with the Mercury Grand Marquis from other model years. Note that the number of problems reported for the 2003 Grand Marquis is 443 while the average number of problems reported for the 16 model years of the Mercury Grand Marquis is 216.