Wildwood4runner

I'm getting close to 160,000 on my 03 4runner..
I posted a few months ago regarding the check engine light.
I followed some advise from some folks here on the forum and went to 4 different places to determine what it was about.
All said it had to be the cat. converters. Eventually all found that 2 of the 4 were bad.
I ended up at what i thought was the best dealer, because there are no aftermarket cat conv avail. Only toyota.
They replaced the front 2, then still got warning. replaces the O2 sensor, then still got warning, ordered another O2 sensor, and found loose wire connection somewhere above tranny. (Is this poss.)
My question is, could it have been loose wire all along. I spent $1,600 trying to get it solved. The dealer was really good to me on the part prices and labor because I was getting a little bent out of shape over the whole deal.
I was told the cats would not have alarmed with the code issued if they were not bad. That they had to be out of spec.
Anyone know any more about this stuff? I obviously am going to keep driving it now that the engine light is fixed. (I could not pass emission inspection here in Missouri with it on.)
I plan on another 100,000 at least. I can live w/ a little sunroof noise, and the seat is a little shakey, but I'm tall so it's lowered to the floor..
So far the 6cyl is running very quiet, the trans is shifting smooth. I drive it pretty hard. Lots of hunting trips thru muddy cornfields pulling a small trailer.
What's next to go?? Any preventive maint. tips..
I was told it had a timing chain instead of the belt so I let it ride. The water pump is making a little noise, but not too bad.
Thanks for any suggestions.
Jeff

ewong

is possible to have loose wiringin the o2 sensor cable.. tho Im not familiar with your era 4Runner.

Cat is generally good for about 100K
02 sensor is also generally good for about 100K

IMHO it is possible that the wiring was loose all along and the cat was in fact good.
It would also be impossible to prove this after the fact.

If you had an ODBII scanner you should have been able to observe the 02 sensor readings (what the EU uses to determien the CAT is bad) and been able to figure out if the CAT was in fact bad or the 02 sensor was bad...

However - since the 02 and the Cat are "wear / service" items and were beyod their specified / anticipated service life - I would not chase down the path of "fixed and didnt need to be".....

chalk it up to the cost of driving a 4Runner...

Look at it this way - if it were a brand X you would be replacing the transmission

Sharp4runr

IMO, O2 sensors go bad more frequently than CATs. They are also much cheaper so you should have looked at replacing those first. But of course hindsight is 20/20 ;-)