my girlfriend bought my 2000 tacoma ext cab v-6 auto from me last july. hence my clever user name. the CES light came on a few months ago. took it to the dealer to have it read, it came up with 4 different codes. the tech said it was the O2 sensor, roughly $300 to fix. located a direct replacement for $100 and put it in 2 weeks ago. now we are having other troubles. it ran fine for months before replacing the o2 sensor. then recently it started hesitating/dying for a second when accelerating from a stop so she quit driving it til i could fix it. immediately after replacing the o2 sensor and clearing the computer it started running funny. it doesnt hesitate as bad but while cruising down the road at steady highway speeds the engine tone changes. it oscillates about twice a second, just a subtle RRR-rrr-RRR-rrr that is barely detectable on the tach. after 50 miles the light came back on. autozone read the code. it did not throw a number code, only said bank 1 was too lean. shes getting very frustrated, as am i since it never gave me a problem in 5 years, and doesnt have the money to have the dealership fix it. any suggestions at all would be so appreciated!!!

 

have you cleaned the maf sensor or change the fuel filter ?

 

What brand of "direct replacement" O2 sensor did you buy? Toyotas are picky about O2 sensors (among other things).

 

i have not changed fuel filters. just heard about cleaning the MAF and am interested in how to do so. as to the brand im not sure. id have to look at the box. it was not denso though if thats where you were going with it.

 

I would recommend the Denso O2 sensor from URD. I would also check the installation and make sure that it did not come loose and that the gasket is properly seated. Oh and check that you did not leave behind the original gasket.

 

That could be either the MAF sensor or the O2 sensor.
If you did not put in a Denso sensor I would highly suggest to do so as well.

Cleaning the MAF may help clear that code for you (may need replacement if cleaning does nothing).
http://www.4x4wire.com/toyota/mainte...tenancep5.html

I presume the CEL code you had this last time was a P0171 - Bank 1, System too Lean

 

While you guys are talking about the (bank 1 too lean code), I had a supercharger put on my 96 runner, it is the older model of the supercharger(grey). Ever since I did so, I get the bank 1 too lean code aswell. But before I put it on it nothing was wrong with it, no engine codes or anything. I did clean the MAF but after only 50 or so miles, the light comes back on. And when I sit at a light she gets a lil rough. If you were to stand outside of the truck you can see her rockin back and forth. My next step is to replace the fuel filter. Do they make free flow ones? Or should I just get one from the dealership? But, because I have a "96" the MAF is 600$+. The guys jaw dropped at the counter when he told me the price on a new one and said that is the most expensive MAF hes ever seen. Aswell as myself. How often to MAF's go bad, considering it was perfectly fine before I put the S/C on??? Thx for the help.

 

jamie- the odd thing about this particular code is that there was no numerical code accompanying the "bank 1 too lean". the person at the dealership said that a bad cat will sometimers do this. looking around on here it seems common opinion, as is mine, it would take alot for a cat to go bad. also i just paid $110 for a new O2 sensor 2 weeks ago, i really hate to spend another $100 on a non-returnable item just to try it. also, is there any info around on how to clean the MAF? i would like to try that.

 

I have never seen a code that came without a number on any OBD II equipped vehicle....in fact I don't think that is even possible for a reader to give no code number (since the ECU stores the codes as numbers). Sounds more like the dealer didn't want to give you the code to fix it yourself. If the CEL comes back you might try taking it somewhere else to get the actual code number. The most common "bank 1 too lean" code is the P0171, but there are others so that code number would still be very good to know for diagnosis.

Here is a link to MAF cleaning:
http://www.4x4wire.com/toyota/mainte...tenancep5.html

Which O2 did you replace (in front or behind the converter)?
was it an OEM part?

 

It sounds like you have some issues with your s/c the way you say it rocks at idle and sounds rough. If you don't have any fuel mods right now, you may want to consider whether you want to spend another 2 grand to get it done right the first time or contemplate selling it. Take it FWIW

 

i checked the MAF last night. it was as clean as the day it came off the line. i shot it with the cleaner though anyhow. i had already thrown the box away so i couldnt find the brand. i cant even remember the brand. its kind of a dead issue anyhow, we have an appointment at the dealership tomorrow afternoon to find the exact problem. it was autozone that read the code before by the way. actually to my surprise our dealership service dept seems pretty cool about doing my own repairs. ill let you guys know sometime in the next few days what the problem was. hopefully this will help someone else out down the road!

 

You may have an air leak.Could be intake or vac line.Mine did, caused bank number 2 to be lean.

 

You may have an air leak.Could be intake or vac line.Mine did, caused bank number 2 to be lean.A new set of ngk or denso plugs probably wouldnt hurt either if its been a while.How many miles on it?

 

we took it in to get the code checked at the dealer last thursday. the problem is somehow i replaced an air/fuel sensor with an O2 sensor. turns out the truck is a california emissions truck. whoda thunkit? never would have guessed in Pa id have one. so now i feel rather stupid and wasted $110 on an incorrect sensor. this explains why as soon as i replaced it things got weirder. several people recommended URD to get parts from, so if he has it ill order one asap!