Bad coils

2001 Focus SE, 125,000 miles. The coil failed and was replaced by a Ford dealership. The replacement also failed but within the warrantee period so the dealership replaced it. Now I’m getting the same symtoms: on Cruise control @ 65 mph. The engine ceases to function for 4-5 seconds and then restarts itself. This happened twice within 10 minutes and once more for a split second 15 minutes after that. It also happened when the 1st coil went out and the 2nd coil as well. The dealer checked the codes and found nothing to explain the problem. He also test drove it for 40m miles but the incident did not occur in that time.

After the 2nd coil but before the 3rd the check engine light came on but the dealer said it was the catalytic converter failure.

Our fear is that this might happen when we are passing, on a high traffic road or in a dead cell-phone area.

We live in Northern Michigan where they salt the roads in the winter.

Same coil every time? If so, the spark plugs and/or wires are likely faulty and at a minimum the spark plugs should always be replaced and the plug wires inspected whenever there’s a coil problem.

A misifiring plug can damage the plug wire which in turn can kill a coil and so on.

The converter can only kill a coil indirectly by causing ignition misfires but it would do this on all cylinders. It will not just pick on one.

It would certainly be wise to check into the plugs and wires as ok suggests. But I also wonder whether or not anyone has searched for a wiring fault. Was each of these coil packs (I’m assuming one coil pack?) actually tested? I.e. the problem might not lie in the coil pack itself but in getting power to the coil pack consistently.

What was that most recent code that you got? It would be in the format P0123 - there aren’t any that can tell you that the converter has failed. There are codes that can point to checking systems related to converter functions. (Either way it is unlikely to be related to the other problem, but the exact code/s would help).