Can bad gas or a loose gas cap cause a P0420 (Cat failure)?
I've got a '97 Grand Caravan 3.3l w/160k miles which I've owned for about six months. I haven't had any issues/problems with it, but then in the last 24 hours the following "weird" things have occurred:
1) My turn signals & emergency flashers quit working. Though I was planning to pull the signal relay to check it, the problem went away and didn't come back (I've put about 75 miles on the van, various start/stops & everything is working fine).
2) Threw a "Service Engine Soon" warning w/code P0420. The light came on when I slowed to ~30mph, after a 20 minute highway drive at ~60mph. The only "out of the ordinary" thing I've done recently is fill the tank today at a "so-so" gas station (the tank was almost empty). Though I normally tighten the gas cap 'til it clicks, I did go ahead and re-tighten it after the code appeared.
Is there a snow-*****' chance these two things are electrically related? I don't see how they could be...PCM is engine control, intermittent turn signals is a relay/fuse box problem. But since both issues occurred in close proximity to each other, I thought I'd ask. Also, can a loose gas cap or cruddy gas cause a P0420? I know that code almost always results in a cat replacement, but I haven't noticed any rough idle, loss of power or hesitation issues; I also passed an emissions test in September.
Thanks for any help!