hi all
i did a post a few weeks back on my check engine light flahing and then staying on codes where 300 303 306 intermitant misfire on cyl #3 #6 i have swap round the coil packs changed the plugs plugs are from the dealer, new wires, i put a up steam o2 sencor in checked for vacum leaks , remember this only happens when i tow my boat (1800lbs) i tow out of od . i am going crazy , i am thinking now i my be the down stream o2 sencor , the flashing is some thing to do with exhaust gases , could it be the two o2 sencors not talk to gether properly , is there a egr valve on a 2000 4runner if so where is it please ,

please please can any one help

 

i doubt that its an o2 sensor, the reason your check engine light is flashing is because of a misfire, and if you continue to drive it like that, you will probably overheat your cat, you may have a problem with the wiring that goes to the coil packs, and i don't think that there is a egr on a 3.4

 

well for # 1 any FLASHING check engine light mean that you will damage your Catalitic converter if you continue to drive. so if you have been driving you probably need a new cat by now. #2 if you have a missfire an 02 senson isn't gonna do ˟˟˟˟. you are probably looking at a coil pack or maybe even injectors. As for the EGR I would imagine that it would have one but Im not possitive, look for a small exhaust tube coming off the exhaust manifold and follow that it will lead you to the EGR valve.

and btw. any OBD2 vehicle (96 and up) will give more specific codes than that. ex. P0419, or P0851, not just 300 or 306.

so make sure you have the right codes.

and good luck.