Any sensor that has 5v feed to it.. such as throttle postion sensor, cam sensor if 3 wire, maf/tmap sensor (depends whats fitted)

On the car I had it on was a Mondeo mk1 V6 years ago.. the TPS wiring was melted against the EGR pipe.

Disconnect the throttle position sensor, then with ign on see if it has 5v on one of the terminals, if it hasn't it points to a short on the 5v reference circuit..it could be anywhere...

Really needs diagnostics doing to see if any codes to help pin it down...