CEL Light, comes and goes Code 25

[romelm]

Light comes on, then goes off. Then I dont see it for a couple of days, then it reappears for a few seconds, then goes away. I finally pulled the code which is 25. Any ideas since the light comes and goes? Thank you All.

 

[Sc0-]

What year? When my truck had this code it ended up having water/corrosion inside the O2 sensor electrical plugs, worth checking. On my '94 I deleted the PAIR and relocated the O2 sensors on the manifolds, zero issues since then.

 

[romelm]

Sorry about that it's a 1994

 

[jonheld]

I believe code 25 is a lean condition, but that's from a 1991 FSM. Your 1994 FSM will have all the diagnostic codes and explanations.

 

[Bullit8169]

Don't mean to hijack but it's an old post and don't want to start a new one. I am having the same code and it's driving me nuts
1994 fzj80 sat in field for 5 years code was there when I first got it runnin. Truck runs great right now

So this it what I've done.

New walbro fuel pump the one everybody recommended to get it running at first
New fuel filter
Did head gasket and cleaned all ports in intake
New vac lines under intake except the bigger one on the vac control valve that goes to charcoal canister
New O2 sensors today
Air intake hose is good
Pair system removed
And I checked everything the FSM says to check for the code. Also I've searched for weeks on this code and haven't come up with a solution so I need some help I am a mechanic but this is my first obd 1 truck.

Thanks y'all

 

[romelm]

Thank you for posting that you have the same issue. Ever since this code has surfaced, I get a 2k idle at start. Once I put it in drive, it drops to 1100 and it feels like the truck wants to "run away" from me. Have to keep my foot on the brake with force. After it reaches normal temp, idle is fine and everything back to normal, however the check engine light is still on. That 2k idle at start everyday cant be good for that motor. I have been driving it with that code since July. I hope someone can chime in and help us both.

 

[Bullit8169]

No problem. I think mine did that also before the head gasket. I also replaced my iac valve gasket I don't remember if that did anything or not. This truck it awesome but it's killing my nerves. My ford nickels and dimes me on parts but these yotas will burn a hole in the wallet if and when you need parts

 

[romelm]

Headgasket?!?!?.....don't scare me like that...LOL! No smoke and no coolant used, thank goodness I know it's running lean which can't be good. I have yet to replace the pair valve, did not even know about that till now.

 

[Bullit8169]

Haha no I did my head gasket because it needed it and I removed my pair because it was falling apart on the inside It made a weird rattling sound and that was one persons solution for his lean code. Not sure if it was bad or not though. That was the first thing I tried.

 

[romelm]

Can I clean the pair valve or does that need to be replaced?

 

[landtoy80]

I have always had the high idle that overpowers brakes at startup.

I believe my intermittent CEL 25 26 is from fouled or ZDDP from Rotella T6 diesel motor oil. I use a bit of oil.
When I drive all hwy I get no CEL. When I drive city, its on all the time. When I do mixed I get the intermittent CEL.

When I cleaned the O2 by soaking them in a solution I found on internet, I passed emissions and had no CEL for several months.


I have over the years just unplugged the O2's when light stays on and later plug them back in and there would be no CEL for some time.

 

[Bullit8169]

Can I clean the pair valve or does that need to be replaced?

removing the egr and pair vsv's

It can't be cleaned. Just fixed I think or deleted