U0173

What it means

A control module has detected that bus C is non-functional and shut its bus C interface off. Bus C is typically a tertiary segment used for diagnostics or specialized subsystems; modules on the segment fall silent simultaneously.

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

• Bus C shorted to supply or ground

  high

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

• One failing module pulling bus C down

  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 U0173 diagnosis, causes & costs
• How to read check engine light codes
• Is it safe to drive with the light on?