OK, so about a month ago my CEL came on. Nothing seemed to be wrong, all was running well. I figured I needed to clean the MAFS so I used sensor cleaner and did just that. I went to autozone and cleared the 91071 code (or whatever the exact number was, system too lean code). I cleared it and it went away, for 6 days. I was driving home and it popped back on again. So I checked the connections, made sure all seemed to be ok. I called a distant friend to see if he could help me diagnose the problem since he owns a small mechanics shop. They gave me a read on their snap on reader thing and said that all SEEMED to be ok. They cleared the code and had me drive around for about 10 minutes to get a drive time read with their scanner. They said it MAY be the O2 sensor, but the reading wasn't quite out of the normal range??? They cleaned the throttle body and the MAFS again really good and said, drive it and see what happens. Well, I left and I drove it for 10 minutes and it came back on again. I went right back they repeated everything they had just done and I left, AGAIN. I got 1 hour away and as I was pulling into my driveway, CEL again and yet all appears to be ok. SO, I have cleaned my MAFS, throttle body, and am still trying to figure out WTF this issue is. Is it most likely the sensor before the cat? With a new baby, money is VERY tight so I have to make sure I get this repair right the first time. $150 is a lot of dadgum diapers. (for the kid you freaks) SO, thanks for reading that novel and any help is appreciated.

PS - Where is a good place online to buy good sensors for a decent price? My local stores want $150 and the dealer wants $200.

 

anyone?

 

This should save you a few packs of dadgum diapers, LOL.
http://www.urdusa.com/product_info.p...s_id=430006000

 

I hear ya on the diapers, man they are $$$$.

Replace the MAF first since often just cleaning it will not solve the issue (95%+ of the time P0171 is a MAF issue). I'd replace the O2 sensor before the cat only after I changed the MAF sensor (MAF on a 99-02 is cheap anyway, 96-98's are more but far less common to go "bad"). If you want to find one really cheap, then get one used from a junkyard instead of paying full price.

It would also help to know the specs on the truck....year, model, engine, etc.

 

x2...
I am having CEL issues as well, the code it keeps trhwoing me is that my o2 sensor after the cat is malfunctioning...
I am getting my sensor from the link provided in a post above me...

But thats as much as I can think of without knowing full specs of your rig

 

I don't remember the price of a fuel filter, but i had the lean code about two years ago replaced the fuel filter and dumped some injector cleaner in the tank hasn't been back since. If it has never been changed that may be a fairly cheap place to start

 

[QUOTE] It was a P0171, system too lean. You hahve a dirty MAF sensor. Running an K&N filter? Clean the oil residue off the wire via brake cleaner. Not carb cleaner! I mean the wire way down inside, not the little thermistor bulb you see. Thats for intake air temp sensor and isnt your problem.

Huh, we sll OE ones for $150, interesting. Try "http://www.autopartspeople.com" and if you click Toyota, use the drill down and it will get you a part. The price you will end up with is 10% over dealer cost!!!!