Over Christmas, my CEL came on. I wasn't in a position to take it to a dealer, so I checked out my first theory a couple hours (and 100 miles) later. I'd had my oil changed a few days (and 200 miles) earlier, and I guessed they didn't put the air filter canister together right. I checked, and that was a problem - the canister wasn't put back on correctly. I put it back together and drove it another 70 miles and the CEL went out after about 2 drive cycles.
A week or so later, the light came on again. This time, I took it to a local Advance Auto and had the code scanned - P0420 (catalyst efficiency below threshold). I took it to the dealer where they told me I needed a new cat - $1100 was the estimate. I figured I'd try replacing the O2 sensors first, incase they were marginal or starting to fail w/o throwing the O2 sensor code. The CEL went out by itself before I put the sensors on...put the sensors on anyway. I drove the car about 600 miles and the CEL came back on. Checked the code again and another P0420 showed up. After a couple days and a few short drives (40 miles or so total) the light went back out again and is still out.
Anyone else had a similar experience? Any chance the incorrectly assembled filter canister could have somehow prompted this to happen??
I'm buying an OBDII scanner on Ebay so I can keep it w/ the car and scan problems on-the-spot for the future, but I'd love to know what the code was the first time...anyway..
If anyone has thoughts on this, please let me know. If I do put a new cat on the car, I'm going to put an aftermarket cat....probably a D.E.C. Anyone have thoughts or opinions on aftermarket cats (good idea/bad idea, problems, best choices?)
Thanks!