U0103

What it means

The Gear Shift Module has stopped transmitting on the vehicle data bus, so other control units no longer receive its messages. 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.

Is it safe to drive?

This code can put the vehicle into limp or reduced-power mode. Avoid extended driving and have the vehicle diagnosed promptly.

Most likely causes

• Shift module unpowered

  high

  One of the most commonly reported causes for this code — check this first.

• CAN wiring to shift module broken

  medium

  A plausible cause — test and verify before replacing parts.

• Gateway module routing CAN messages incorrectly

  low

  Less common, but worth ruling out after the more likely causes.

Related help

• Full U0103 diagnosis, causes & costs
• How to read check engine light codes
• Is it safe to drive with the light on?