Need Help.My Taco is CRAZY! or Maybe its me LOL

I have a 2000 Taco V6 4x4 auto xtra cab about 2 months ago it threw a code had it scanned said it was 420 & 171 (needs more dank) LOL well about 2 weeks ago the check engine light went off . Than about one week later check engine light comes back on.,Sat this past weekend was driving along the 101 and it just died on the 101..Like some1 turned it off the engine just died when i attempted to restart it acted like it was flooded and wouldnt start , Had it towed home by AAA and looked under the hood saw nothing checked all the fuses tried several times to start and it would turn over and than die. So at home looked it all over and nothing! Went underneath by the tranny where there are several sensors wiggled them and saw nothing wrong. So for shits and giggles attempted to turn it over and it started right up. Placed a scanner on it and all the codes have been wiped out and now the check engine light is off and it is running great better than ever. Any suggestions how this could happen??? Thanks

 

Well, 171 is system too lean and 420 is bank #1 catalyst efficiency below threshold.

With a lean code, you might have a vacuum leak somewhere (?) Intermittent issues like that are usually either an electrical short or maybe a vacuum hose that's torn, but only leaks when hot or something. Could be a bad sensor, too. but you might want to try and research causes of those error codes first. I'm no expert, I just google stuff. ;-)

Weird that the codes are gone. Codes usually stick around until you manually clear them with the reader. I'd suggest leaving the reader plugged in while you drive and see if it happens again.

Here's a link to some codes I found. It's a corolla forum, but the codes listed are universal.
http://www.toyotanation.com/forum/135-corolla-lounge/148676-obd-ii-trouble-codes-full-list.html

 

hey thanks alot well it wiped all codes out the prior and the present and now runs great I just have NEVER heard of the codes just wiping themselves out nothing in the brain no stored past codes I just dont get it

 

and NOONE manually cleared them

 

My truck did a similar thing when the fuel pump went out. Just shut off. Started back up and drove some more then it shut off again and wouldn't start.

 

Hi well mine even passed emissions not sure how but it is running great so I don't know what is going on but I have never ever had any car or truck erase all its memory in the brain like all present and previous codes like it never ever even throw a code...very odd...

 

Like stated above it is more than likely a vacuum leak. The air boot that goes from the MAF (mass air flow sensor) to the throttle body has the greatest potental for leaks. It usually cracks at the throttle body connection. The cranking and then stoping is going to be a tough one to diagnose properly. You dont want to start throwing parts at it.

 

a loose connection at MAF sensor can act like that, night not be your problem but I would check all the electronics under the hood are plugged in good.

the funny thing is codes clearing by themselves shouldn't happen so it might be the ECM is going out on you, I have no idea how you could check THAT