CEL Subaru Forester 2002

the check engine light comes on (and stays on) regularly. Last year replaced catalytic converter etc. this year went back to pass inspection with CEL on - they did the computer test and concluded I need a new catalytic converter. Is this possible? I am going to auto zone to get the computer number and can check back- but a new cc in one year seems questionable. any advice?

You need to have the codes read. Some places will read them for FREE. Try Autozone or Advanced Auto Parts.  [b] Get the exact code (like P0123) not just their translation[/b] into English and post it back here.

If you are having “combustion issues”, it is possible for a cat converter to go bad in just a year. My guess is that your mechanic did not repair the underlying issues last year when he replaced the CC.

If this car has not had ALL of its maintenance done on schedule, you need to do this for a start. Once it has new spark plugs, plug wires, new filters, etc, it will be much easier to diagnose the underlying problem leading to CC problems. And–it is just possible that proper maintenance will resolve the situation leading to CC problems.

code: PO402

That code indicates a problem with the Exhaust Gas Recirculation (EGR) valve.
When the EGR is screwed-up, it can lead to all kinds of problems with combustion.
Combustion problems can lead to CC problems.

Have your mechanic check the EGR carefully.