My check engine light came on today. I pulled codes 25 and 26 of the computer. The 25 code is a lean condition and the 26 code is a rich condition. I had a rich condition on startup with some backfire on decelleration when I ran it a while w/o a converter. I put the converter back on and drove it about 50-60 miles and the light came on. Since I put the converter back on there has been no backfiring and the rich condition seemed to be gone??? There is about 1000 mile on the rebuilt engine. Maybe I fried the 02 sensor when I was running without the converter. Are these two codes most commonly a O2 sensor? Any other ideas?

Addional info: After searching about 20 more posts, I am going to try to pull the EFI fuse to reset the computer to accept the new readings the o2 sensor is probably putting out due to the converter reinstall. Hope it helps.

 

hey man i had the same problem with mine but i only had 25and i ran the code and it is the air fule ratio lean malfunction(25) and air fule ration rich malfunction(26) could be a coupple things: engine ground bold loose, open in e1 circut, open in injector circut, fuel like presure blocage ( little or no fuel) open or short in o2 sensor (oxygen sensor), o2 sensor, igniton system, water temp sencorm, air flow meter(air volume meter)(mas airflow sensor) or the TPS sensor (throttle positioning sensoer. i read thoes from the toyota codes manual from the offical toyta manual. my problem happend to be no backlash on the valves and no compression in 3 cylinders so u might want to run a compression check but you probably wont have the same problem as me. i think it is very comen to get these codes with a fried o2 sensor becaue the engin myght be triped out and try and compensate to pass smog or something. hope this will help!

 

Well, I reset the computer and we will see if the light stays off tomorrow. I am leaning more and more to the o2 sensor. I think fuel consumption is up, but could not say for sure. I think the o2 sensors go to full rich when they go bad.