paynemw

I have a 2000 4Runner SR5 4x4 5speed man trans. I recently purchased it and my check engine light came on. I got Advance Auto to do a reading and it popped P0420 Oxygen Sensor Below the Threshold.... aka below the cats. Also my exhaust was rusting out so I went to get a custom magnaflow put on with cat replacing the California spec two cat system. When i was getting it replaced I noticed that the upper O2 sensor was new and the lower was way old. After replacing the exhaust and clearing the check engine light the check engine light came back on so i replaced the lower O2 sensor, it has come back on again. So I'm guessing either a couple things; 1. my lower O2 sensor is bad 2. the new mixture because of my lower restriction exhaust is outside of the ranges that my computer will read 3. the O2 sensor is not properly installed What do you guys think/could someone help me out!

FogRunner

Unless you go back with the toyota OEM cats your computer will keep throwing the P0420 code. The vast majority of aftermarket cats are no where near as efficient as the Toyota OEM ones.

The simple solution is to buy a O2 sensor simulator from URD and it will modify the signal from the O2 sensor to make the computer thing the cat is working at 100% efficient all the time. I've had to go the route because I refuse to pay for a califoina standard cat from Toyota when I live in Texas.

paynemw

thanks brotha, i appreciate it.... i figured that was the problem

YotaNewbie

Now you just need to go find the guy who sold you this 4runner and beat his face in with a baseball bat. Anyone who disconnects the battery so they can sell a car without the check engine light on is fair game to be killed in my book. I put more than $2,000 into getting that CEL to go off in my dash, and if I ever really hit rock bottom I'm going to literally - and this is no joke - put a bullet in the guy who sold me the car's head.

paynemw

haha, yea the used car lot i bought it from was pretty shaddy, but i wanted a 2nd or 3rd gen 4runner that was manual and i didn't have alot of time because i was moving from fort benning to fort sill so i bought that one... i've done alot of maintenance just to get it right... real seals new rear brakes new exhaust new O2 sensor, i did the intake silencer elimination mod, i need new plugs and wires, atleast he sold it to me with nice goodyears... but i'll replace those when i get enough money for an ome lift... i've spent some money but damn its gonna be bad (to the bone?!?)