Serial Identification Number
IMPORTANT: Always obtain the serial number when possible. The serial number can help determine the engine model and help determine the correct service parts and changes based on serial number breaks.
Old Format
4-6 numbers that are sequential with no breaks for production month or year
New Format (starting 1997)
Alpha-numeric (e.g. XJ5050 or 4J5050) with breaks for production month and year
FIRST DIGIT = PRODUCTION YEAR
| 1997 | 1998 | 1999 | 2000 | 2001 | 2002 | 2003 | 2004 | 2005 | 2006 | 2007 | 2008 | 2009 |
| V | W | X | Y | Z | 1 | 2 | 3 | 4 | 5 | 7 | 8 | 9 |
SECOND DIGIT = PRODUCTION MONTH
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
| A | C | E | G | J | L | N | Q | S | U | W | Y |
| B | D | F | H | K | M | P | R | T | V | X | Z |