Generic
Type:
    Powertrain - Transmission - ISO/SAE Controlled
Description:
    Engine Speed Input Circuit No Signal

GM
Type:
    Powertrain - Transmission - ISO/SAE Controlled
Description:
    Engine Speed Circuit Low Input Conditions
Cause:
    Key on or engine running, then the PCM detected an internal fault. Note: If PO5OO, P0721 or P0722 are set, repair these codes first).