Shop tells me they can't diagnose if intermittent problem is not currently happening. True???

Question

Code P0353 Ignition Coil Malfunction. Mechanic traded out #3 to #1 to see if problem was coming from the coil itself. Now I keep getting the same message (still #3), and the car misfires intermittently, but never when I take it in to get it checked. Service writer has told me they can't check the problem if it's not currently happening. Could this be correct?

Answer 1

P0353 Igniter cyclinder malfunction

By swapping out the coil that is a good move to do. It just prove the problem reside with the ECM.  When it comes to intermittent problem it is always a good idea to get it check when it is happening. the most difficult is when it is a intermittent condition