What U0404 means
The Gear Shift Control Module is present on the data bus but the values it reports are implausible — out of range, frozen, or failing the checksum or rolling-count check.
How the engine computer detects it
The receiving modules reject the data. Shift-by-wire gear selection may be wrong or blocked. Causes include a faulty sensor feeding the module, internal computation errors, a software or calibration mismatch after a repair, or bus interference corrupting the frames.
Written from public technical sources and not yet checked by a mechanic. How we write these pages
Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
Common causes
- Shift module internal fault Possible
- CAN corruption causing checksum errors Possible
- Gateway module routing CAN messages incorrectly Less likely
How to diagnose U0404
- Read every stored code with an OBD-II scanner. If misfire or fuel trim codes are there too, fix those first: they often cause this one.
- Inspect the parts involved: gear shift module, can bus wiring.
- Work through the causes above from most to least likely, cheapest checks first.
- Clear the code and drive a full drive cycle to confirm the repair held.
Vehicles that report U0404 most
| Vehicle | Years | Reports | Share | Median miles |
|---|---|---|---|---|
| Jeep Grand Cherokee | 2005–2007 | 9 | 57k | |
| Jeep Commander | 2006–2007 | 3 | 51k |
Counts of owner complaints to the NHTSA that mention U0404 (16 in total), not failure rates: popular models get more complaints simply because more of them are on the road. Models with fewer than 3 complaints are left out.
Reading the code
- U
- Network
- 0
- Generic (SAE) code
- 404
- Specific fault
Questions drivers ask
Can I drive with code U0404?
It depends on which module stopped communicating. If the car drives normally, drive carefully to a shop. If the engine, transmission, brakes or steering act up, or many warning lights come on at once, stop and have it towed.
This page is general information, not a substitute for a professional diagnosis. Repair costs are rough estimates for parts and labor and vary by vehicle and region.