What are the first things I should do when my car is throwing code 25 and 26? I have seen some threads on this, but i wanted to address the first things i should do to trouble shoot this problem. thanks guys

 

maybe you could tell us verbatim what "the book" says about those codes? The DTC book usually have a distinct way of describing the codes and possible causes. If it's a rich/lean problem like your title says perhaps start by looking at your o2's.

 

code 25= lean code 26=rich

 

You got a 1992 SC400, check your O2 sensors.

 

should i just buy new ones? I am not quite sure how to check them. what other things can cause these codes? Is it probable that it is the o2's?

 

You can take it to the dealer and let them do the " O2 RPM check" by using the scan tool and they can see the wave form on the scan tool. A new O2 may cost you around $200.00 each, plus labor.

Please search for another thread that related to " O2 sensor" in the " Search ".

 

Anyone else here ever throw a code 25 or 26 (running rich and lean)? and how was it fixed? thanks guys

 

This was for ls400, 1992, 178,000 miles.

I replaced o2 sensors, no luck.

Did a tune up, caps,rotors, spark plugs. Rich condition fixed -I guess new plugs helped that, but lean condition remained. Changed fuel pressure regulator (part# 23280-50010---$103.43 from irontoad.com) and all codes clear now.