Diagnostic Aids

WARNING: This page is about a different car, the 2003 Pontiac Grand Prix. However, it is still accessible from the selected car via links, so may be relevant.

This DTC may be stored as a history DTC without affecting the operation of the module. If stored only as a history DTC and not retrieved as a current DTC, do not replace the module.
If this DTC is retrieved as both a current and history DTC, replace the module.

Fig 1: DTC C0550 Diagnostic Table

Courtesy of GENERAL MOTORS CORP.