DTC P1624: Transmission Control Module Request "Check Engine" Input
WARNING: This page is about a different car, the 2000 Saab 9-5 and 1999 Saab 9-5. However, it is still accessible from the selected car via links, so may be relevant.
This DTC is set when automatic transmission experiences shifting problems and requests ECM to turn CHECK ENGINE light on. For diagnostic procedures, see appropriate ELECTRONIC CONTROLS article in AUTOMATIC TRANSMISSIONS.