Toyota's engineers just made me crazy....

Why are the O2 sensors before both cats or after both cats?!?!?!?!?!    They should have put on between them so you can determine which catalytic converter is bad.  I've got the P0420 and the shop today told me that the O2 sensors are working correctly, but they can't tell which cat is bad! AHHHH!!

Nearly $900 to replace both cats, since the first cat needs to be a direct fit one (should fix the CEL).  About $300 to replace the second cat w/ no guarantee that will remove the CEL.

It's about $100 for this option to trick the CEL and pass the OBDII emissions test, since they don't sniff the tail pipe.

URD O2 Simulator

Any of you guys familiar with this? Heard anything about it?

That sucks. I guess you should move to Box Elder and not worry about it!

Did you get your radiator swapped out yet?

Are your cats welded in place? If you have an easy way to remove them, I have a brand new high-flow 2" inlet/outlet cat you can use to see which one is the problem.

Get a new muffler shop. They can put a hole in the pipe between the mufflers and put a sniffer in - they can tell you exactly which cat is bad, they just don't want to.

Brad, the Radiator swap is done. It showed up last week and didn't take long to get put in.


Andrew, I'll have to get under there and look to see how easy the cats are to take off. I think the 1st one needs to be an exact fit, the 2nd can be universal. I may take you up on the offer.


Kevin, I'll check around and see if any shops will do that.

Just saw this - http://www.toyota-4runner.org/3rd-gen-t4rs/175242-how-make-your-own-rear-o2-simulator-%245.html

Good find Kevin! That looks fairly simple, and for $5 it's worth trying out.

So apparently you have a wideband in front, Brady, and the ECU uses the signal from the rear O2 sensor to calibrate it.  Looks like the jury is out on whether or not that will work with the O2 simulator mod in place?

You probably should just junk it and buy Andrews truck.

I still might give it a shot. If it doesn't work, I'm no worse off.

Didja fix it yet?

http://www.toyota-4runner.org/sale-t4r-items/176237-fs-3rd-gen-oxygen-sensor-simulator.html

Kevin wrote:Didja fix it yet?

http://www.toyota-4runner.org/sale-t4r-items/176237-fs-3rd-gen-oxygen-sensor-simulator.html

Pulled the sensor and wired up the resistor and capacitor. Got everything plugged back up, but got busy taking the ball joints apart so I haven't turned it on to see if it worked.

In case anyone needs this in the future, it worked. Cleared my CEL for p0420.