Trouble Codes 25,26, and 28 (1 Viewer)

[Kawika]

My check engine light came on about a week ago in my 1993 LC. I pulled the code and it gave me the 28 (O2 sensor). I looked into ordering an O2 sensor, and also tried resetting the computer by disconnecting the battery for a couple seconds. The light stayed off for a day, and now the truck is hesitating and and running rough. It doesn't stall, but lets me know that it doesnt want to be put under load. I had to drive the LC the next day to work and to pick up the O2 sensors I was planning on changing. I figured this was caused by the bad O2 sensors (if they turn out to be bad). Anyway, the check engine light came on again, but this time it gave me both a 25 and a 26. Is there any significance to the sequence of the trouble codes? 28 then 25 and 26 simultaneously. Any suggestions on how to diagnosis this problem. I'm at a 100,000 miles and from what I've read on the board and in the FSM, that seems to be the life of the O2 sensor, so I was planning on changing them anyway
Thanks,
Kawika

 

[AZcruiser]

do a search, this topic was discussed about a month ago. I had a 26 2 months ago, cleaned the EGR and throttle body, took of the K&N air filter and no problems.

 

[Kawika]

Az Cruiser,
I did a search and had read your thread. I thought maybe the sequence of the codes might be relevant to the problem. Thanks for your suggestions.

 

[landtoy80]

Could be carbon build up, exhaust leak (pre the cats) dirty injectors.
Replace the O2 and see what happens.
I you still get 25 26, get a can of Toyota FI cleaner, clean your throttle body and Seafoam through the PCV.
One or all solved my 25 26 problem.