U1073 - SCP Invalid or Missing Data for Engine Coolant
- Faulty / intermittent ignition switch connections
- J1850 / SCP Bus wiring intermittently open, shorted to power or ground
- Faulty / intermittent connection at the Powertrain Control Module (PCM)
It can occur if:
Someone changes a battery while the ignition switch is left on, that is, left in the “Run” position.
Someone flashes/upgrades their engine controller – other modules unable to communicate with PCM during this process – this will set U1073 at a multitude of controllers on the vehicle – all false codes. Erase and carry on.
When is the code detected?
- Engine Light ON (or Service Engine Soon Warning Light)
- Engine cranks but may not start – may be intermittent
- May or may not be able to communicate with a scan tool / depends on problem
This is a manufacturer specific fault code and can be used for several different faults, depending upon what the manufacturer wants to use it for. The Powertrain Control Module, or PCM communicates over the Serial Communication Protocol (SCP) bus network, or J1850 bus. This is a medium-speed bus communication system and is fault tolerant, which means any type of intermittent/loose connection at these controllers will cause this code to set in memory, but will still operate, provided a data path is available. When the PCM is unable to communicate with any other controller at any time while the ignition switch is turned on, code U1073 will set. This is the typical reason for this code to set.