Subaru Repair: CEL, catalytic converter, timing belt

Question
Hi Nathan,
Came across with this site and found it's really helpful. I have a 03 Forester MT with 160k. Had timing belt and pump replaced by my mechanic at 130k. Don't know if it's coincidence or not that the CEL light came on later and the dealer said the converter need replacement (forgot code). I found the converter is so expensive and there's no after market ones available.
I'm wondering if the CEL has something to do with incorrect timing after replacing t-belt as I found out in a Subaru forum. Sometimes after a long trip the rpm fell to about 600 when idling. My mechanic idling should be set as low as possible as long as the car won't stall to save gas. Is that true for my car?
Thanks a lot.

Answer
These cars often have the catalyst inefficiency codes, and that means the catalytic converter is not working efficient.  I wouldn't think the timing belt would have anything to do with the Check Engine light, but it might.  If you don't trust your current shop, wait for the light to come back on and take it to another shop and get a second opinion.  I am not sure about you idling problem, the catalytic converter could have something to do with it.  Always eliminate known problems before diagnosing unknown problems.  Hope I could help you!