u/unevocative

I had the timing belt/water pump, radiator, fan clutch and pulleys/tensioners replaced last week. Drove it on a road trip of 1,100 miles Sunday-Tuesday and it ran/drove great. Ran a couple of errands today and everything was fine, then pulling into my driveway the CEL came on and it's throwing P0420. Just a coincidence, or could it be something off from the timing belt job? All four O2 sensors were replaced with new Densos about 6,000 miles ago.

• Editing to note that I've decided not to do the timing belt myself. I will screw something up. I've thought about having a shop do the timing belt and water pump, seals and thermostat and then doing some of the other stuff myself, but the shop i use is pretty good about not adding a ton of labor charges when they've already got something apart anyways*

I'm getting ready to do the timing belt on my 03 that has almost 180k on it. I rebuilt the entire front end last year and just put new tires on it yesterday, so at this point I'm all in. I'll be using the Aisin kit for the timing belt, water pump, tensioner, and pulleys, and already have the thermostat and gasket, water inlet housing O-ring, heater hose Ts, camshaft seals, and crankshaft seal and bolt. I figured while I'm at it I'm also going to do the following:

- fan clutch bracket (going to use the Aisin)

- radiator ( from the dealer)

- radiator hoses (dealer)

- serpentine/v belt, tensioner, and idler pulley (dealer except for the grooved idler pulley that's NSK)

Now, should I also replace the fan clutch itself? How about the fan? If I do, I'm probably going to use the Aisin fan clutch and an aftermarket fan, despite usually using factory parts on everything else I've done to this thing. Anything else I should consider doing at this time?