Cam install, one week later: while driving in the rain today, I got a check engine light while cruising gently uphill: P0420 set, another P0420 pending. I cleared the codes to see if they would return, and they didn't. The code means that I either have a massive exhaust leak, my rear O2 sensors are showing too little change, or my cat is dying.
(Less than a month before my emissions test, and I get my very first emissions-related CEL. It figures.)
Here'* what I've looked at and what I plan to do:
- I've noticed no loss of top speed or power, so I'm guessing my cat is fine. Last time I gave it a good knocking (during the cam install), nothing rattled.
- I reused the exhaust pipe gasket when reinstalling the engine, because it was in good shape and not flattened. I'll replace that the next chance I get.
- I checked the fuel trims and the voltages of the O2 sensors at idle and while cruising (25-35 mph), but that was pointless, seeing as how I don't know how to interpret the data.
Anything else I should check out?