It costs $50.00 charge to diagnose a car.
The reality is that the majority of the time it takes a lot less than one hour to diagnose the issue but you still end up paying the same fee. Instead we would charge the actual time it took to diagnose the vehicle (Ex: $100 per hr. and it took 30 minutes to diagnose = $50.00 charge) and you should insist upon the same.
Most auto parts stores will read the computer trouble codes for free as they want to sell you the part or parts to fix the problem(s).
Depends where u go, cheapest I've seen is 45.
There are quite a few auto part stores and shops that do free diagnoses ammco transmission some Midas shops as well
Once the codes are read and more time is needed to verify what is wrong an hour labor is minimum. Electrical problems are time and materials and there is no set cost because it could take hours to pin point the problem in the wiring or computer.
$60 seems to be the average but most shops will apply that toward the final bill if you have them do the repair.