Check engine light came on, Autozone says P0420 code. Cleared code and hasn't came on for 5 days.....however, car stalls out and won't restart until it cools. is it the cat? will run fine for a day or two, then stalls out and won't restart. 97 civic car runs fine otherwise....

 

When the engine won't start, do this:

1) Listen for whether you can hear the fuel pump prime (low humming noise in rear) for 2 seconds when you turn the key to ON(II).

2) Turn the ignition key to ON(II) and watch for whether the CEL turns ON and then OFF after 2 seconds or remains ON.

3) Check for spark at each spark plug. Disconnect a plug wire from a plug and insert a spare plug into the end of the wire. With the plug threads firmly grounded on the valve cover, have your buddy crank the engine. You should see bright bluish spark (not weak orangish spark) at the tip of the plug.

Post the outcome of these tests for more feedback.

 

1) YES - (low humming noise in rear) for 2 seconds when you turn the key to ON(II).

2) NO - CEL turns ON and then OFF - does not remain on

3) spark ok

 

The car not restarting until cool sounds like a main relay. But the converter could be plugged too, I've seen that before.

 

thank you......I did change the main relay switch......still no improvement.

Can the cat be cleaned??