O2 sensor issues.. Local mechanic's thoughts.

[RUNMYTA]

I have just about given up on getting the CEL on my 99 Limited Cali ED. Fixed.:redbrick: First I had a Code P0125, so I replaced the Air/Fuel Sensor with a brand new Denso. Within 10mins of start up the CEL came back on and now has a code P0135 O2 Heater Circuit (P0125 is gone). So I take it to a local shop and ask them if they could check it out for me, explaining what I have read here and that there might be an issue with the wiring etc..

Mechanic preceeds to tell me he is willing to bet that it is Ethonal in gas. His thought process is that if the Cali model doesnt burn exactly what the ECM has it will throw an O2 code. He advised me to run down to almost empty and try to fill up with NO Ethanol fuel 92/93 octane...

What are your thoughts on this theory???

 

[badattitude]

I like to buy no ethenol as a standard practice when I can. Can't do it every time but I can get 87 octane 100% gas from time to time. The Cnex gas stations still have 87 100% gas.

Sounds like good advice to me. Anytime a mechanic has advice that dosn't involve paying him, it's good advise, lol

It's too easy not to try.

 

[LittleCaesar]

Can't hurt. My mpgs have decreased since using ethanol gas. Yea for CAFE, EPA, and politicans.

As bad as it is for me, my buddy has an old Boston Whaler with the original fiberglass gas tank in it (made prior to 1984). Thanks to the ethanol settling at the bottom since it attracts water and then attaches to water to become heavier than fuel, the gas tank became quite porous to say the least.

Also, for all those like me who use their 4runner as a secondary vehicle as well as for all sedentary motors, make sure to try and use 0% ethanol gas since ethanol dissolves old gum and varnish in fuel tanks and clogs up injectors, filters, and the like.

 

[Bamf_CT2004]

Are you sure you got or were given the correct o2 sensor? There are few different variations and could be easily mixed up.

 

[TheDurk]

P0135 is a very specific code--the heater circuit in the O2 sensor is either open or shorted. This is likely either a bum sensor out of the box, the wrong sensor, a bad connection, or other specific electrical fault. There is NO WAY fuel type has anything to do with this particular code, and if your mechanic thinks so, HE is a part of the problem.

Take the silly sensor out and test the heater resistance with a DMM. Check that it's the right one. Verify your connection. This is an easy fix.

 

[Smog-guy707]

^+1 on that. ive replaced many 02 sensors that have came deffective. if he used a universal, he may have wired it wrong. if he used a oem fit...it may be bad...or the heater fuse may have gotten blown.