First off I know this is my first post and I have searched. I just purchased a 92 sc400. Soon as I get home from 2 hour drive from the dealer cel comes on. I don't panic because I know my way around a car but damn. So many different option from 2 codes. Where would you begin? By the way the car has 130,000 miles and it sort of spudders at idle. That tells me running lean. Sc Gurus get in here!!!

 

25 is air fuel ratio lean malfunction
26 is air fuel ratio rich malfunction

From the sc300 manual the two things that both have in common are a difference of air-fuel ratio between two groups of cylinders, probably between the banks of cylinders on the 400. There's a compensation value and if it exceeds 15 percent for 20+seconds then the light goes up. Areas to look for are injector circuit, fuel line pressure, timing, ignition, compression, air flow meter.

Another one is that the engine varies it's rpm by 15+ rpm after the previous crank angle. Same areas to look for.

 

I got that far... I guess I'm looking for the first steps in pin pointing what is making it lean. Could it be from not using premium fuel. Not my self just assuming the dealership?

 

I've done a bunch of searching on this since I have Code 25 right now. After lots of searching it seems 90% of the time its the 02 sensors.

I have Code 25 on my 92 SC400. My CEL and TRAC light come on after driving on the highway. If I clear the code, I can drive around all day long for weeks in city traffic but the lights won't come on. If I go on the hwy for a couple minutes then the CEL and TRAC light come on.

Can anyone help with this one ?

 

I was kind of hoping it wasn't the 02 sensors almost 2 hundred a piece. ANy help will greatly be appreciated.

 

Cheap fix. I ran fuel injector cleaner throught 4 fill ups and an octane booster I forget the brands but totally fixed. Car idles great and power is restored. This may help others too.