U0304Software Incompatibility With Gear Shift Control Module
- Generic OBD-II code · Network
- Can trigger limp mode
- How the car detects it
- U0304 is stored when a control unit, usually the transmission controller, finds that the software or calibration identity of the gear shift control module does not match what it expects. GM's generic U03xx procedure (Saab 9-5, 2011) treats such codes as configuration faults: checked at 9-16 V with normal bus traffic, no circuit test, cured by setup or programming. Allison uses U0304 for its 6th-generation controls as Gear Shift Module 1 Incompatible: a 6th-generation push-button selector does not work with a 5th-generation TCM, and the selector must match the TCM calibration; U0333 covers selector 2. U0103 means lost contact, U0404 invalid data from the same module. The driver may be unable to select a range.
- What you may notice
- Gear ranges cannot be selected or the selector does not respond
- Transmission warning or code shown on the selector display
- Code appears right after a selector or TCM was replaced
- Likely causes
- LikelyShift selector generation or type does not match the TCM calibration (e.g. after replacement)
- PossibleShift module or TCM replaced or flashed without setup
- RareSoftware update aborted, wrong file loaded
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €80 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.