What U0103 means
The Gear Shift Module has stopped transmitting on the vehicle data bus, so other control units no longer receive its messages.
How the engine computer detects it
Shift-by-wire gear selection can fail and leave the transmission in a default position. Typical causes are loss of power or ground at the module, an open or shorted CAN/LIN bus wire, a connector fault, or an internal module failure.
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 unpowered Most likely
- CAN wiring to shift module broken Possible
- Gateway module routing CAN messages incorrectly Less likely
How to diagnose U0103
- 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.
Reading the code
- U
- Network
- 0
- Generic (SAE) code
- 103
- Specific fault
Questions drivers ask
Can I drive with code U0103?
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.