Engine Code 25/26

[sierra1boy]

1994 Land Cruiser

Hi Guys,

I know this topic comes up a lot and I've read pretty much all I could find on the forum about it. I feel like my probably is just a bit different in that I haven't seen anything that has this repeatable pattern s I'm posting it once more just in case someone has experience with it and can suggest what else I can do for troubleshooting. So far, I have gone through and tried to identify any vacuum leaks through the engine, along with any cracks or non-air tight fitting around the full intake. My idle seems to be normal and my power level, while low, seems to be correct for this motor. I have also disconnected the battery for a few days just in case it was some old code that kept popping up. Here's the pattern that I'm noticing: When I start it up I will not get the engine warning, however, if I idle too long (say 5 plus minutes) then the warning light will come up. Once I get on the road and drive for another 5 minutes or so, the warning light will go away and not come back the entire time I'm driving. Then once again if it cools down and I idle to long it will come back. Also, the engine performance doesn't seem to change in either scenario. Any thoughts you have on troubleshooting it further would be appreciated. Thank you

 

[jonheld]

1994 Land Cruiser

Hi Guys,

I know this topic comes up a lot and I've read pretty much all I could find on the forum about it. I feel like my probably is just a bit different in that I haven't seen anything that has this repeatable pattern s I'm posting it once more just in case someone has experience with it and can suggest what else I can do for troubleshooting. So far, I have gone through and tried to identify any vacuum leaks through the engine, along with any cracks or non-air tight fitting around the full intake. My idle seems to be normal and my power level, while low, seems to be correct for this motor. I have also disconnected the battery for a few days just in case it was some old code that kept popping up. Here's the pattern that I'm noticing: When I start it up I will not get the engine warning, however, if I idle too long (say 5 plus minutes) then the warning light will come up. Once I get on the road and drive for another 5 minutes or so, the warning light will go away and not come back the entire time I'm driving. Then once again if it cools down and I idle to long it will come back. Also, the engine performance doesn't seem to change in either scenario. Any thoughts you have on troubleshooting it further would be appreciated. Thank you

25/26 is likely O2 sensors or associated wiring. Since the connectors for both O2 sensors are under the truck, I would start with a good cleaning and go from there.
To clear error codes and reset the ECU, remove the 15 amp EFI fuse for about 5 minutes or so.

 

[CharlieS]

My 25/26 went away with new O2 sensors.

You can test the O2 sensors with a multimeter and oscilloscope, using procedures in the FSM.

 

[sierra1boy]

Thanks Guys, I'm going to take your recommendations and do both this weekend