Does anyone have a suggestion on where to start first on the code 12? Also why would I be getting a code 25 and 26 at the same time?

 

im having similar issue any feedback ?

 

Never got any feedback. I did disconnect the battery and the code 12 stopped popping up but i still have a 25 and 26 at the same time. Those two only come up when I am driving at highway speeds.

 

mine seem to pop up after hard acceleration to breaking or slowing to turn off highway !!!! , my light used to shut off but it seems to be steady today, im gonna walk through the book and i will tell you what i find,

 

Does it effect the performance at all?

 

i think im getting bad gas milage about 200 miles to a tank and i noticed on a road trip after it was good and warm it would die at stop signs, and run real rough for a min after i restarted it

 

I think i am getting bad gas mileage but that is it.

 

by chance do you know what these sensors are ?

 

where are they located

 

on the back of the throttle body close to the firewall the one without a wire the wire was loose and coroded it also looks like the conector on the wireing harness is broken off .... i cleaned the connection and so far no check engine light... gonna reset the ecu tomorrow and see if it fixes it???

im hoping its the temp sender telling the engine to use the egr system causing a lean and rich fail but i have a feeling its a long shot.... While going through it loos like the previous owner replaced a lot of the system already. but again im not to sure

 

does your truck have a cat ?

the stealership said check o2 and maf sensor

 

now im getting to the nitty gritty ....
light came on again got no answers from parts store and a little from toyota i re plugged in that wire on the above pic to the sensor there only one wire to it. i believe its a water temp sensor according to the diagrams i have found

after i replugged in the wire the second time seems to have shut off the light .... more info to come if the light comes back on but below are some links that helped me with the chasing down of the system i hope they help you too
Diagnostics scroll down to code 25, 26 there are refrences to page numbers that have broken links
here is the pages its refering to



oops above is for 22r
diag
pages

test for O2
Part location diagram

 

i got the check engine light out.... though it was a new engine that did it let me tell you what i found.... in the above picture with the sensor above there was a cheap wire connector attached to the original blue wire to a thicker black and yellow new wire....

i cut and soldered that connection also there was an exposed wire to the number 3 cylinder injector.... cleand and fixed that connection

in the number 6 valve i found a bolt, a bolt which i believe sat in the intake plennum and rattled its way down there and caused engine to not function any more

also compression was low in three cylinders and the intake was coated in oiil and carbon buld up.... the intake tube was also filled with a gooy gunk

conclusion
I believe the bolt disrupted the air flow to the number 6 cylinder causing an occasional miss firing causing a lean and rich problem in the engine ....

with engine running get a stethascope and listen to each injector and see if it ticks inside ....

If i were you i would pull the plennum and clean out the inside of that and your intake manifold.... inspect injector wiring and see if anything needs to be cleaned up also check the wiring on the sensor in the pics above .... make sure nothing falls into the intake plennum and look towards the valves and see if there are any obstructions to the cylinder

I hope this helps
Geoff