June 7, 2004
2004 Twin Cam Combustion Codes
There have been reports that some production 2004 EFI Twin Cam vehicles
intermittently set codes P1353 and P1356. These vehicles were stock and had no
driveability issues. An investigation determined that the 2004 ECM calibrations may
allow these two codes to be set without any actual combustion problem. Calibration
changes correcting this potential issue went into production vehicles built after May 3,
2004.
The revised calibrations are included in the Digital Technician software, version 12,
recently shipped to your dealership.
Although rare, it is possible to encounter either or both of these codes on a stock,
production 2004 Twin Cam vehicle built prior to May. If so, simply download the new
stock calibration using Digital Technician then file a warranty claim for labor in the
normal manner using Job Time Code 7931.


Source: http://www.harleyhog.co.uk/