Folks: My 92 XJS 4.0 had the check engine light come on but after start and stop it did not return. Meanwhile the Trip Computer registers Fault Code FF26.
The handbook says this (FF26) is "Air Leak: looks for poor feedback control in rich direction" while the Haynes manual for the XJ6 says "Oxygen Sensor circuit: Lean Exhaust Vacuum Leak".
There is no mention of the seriousness of the fault, and so my fundamental question is whether this means the car should be driven as little as possible and be into service ASAP or if it is minor and can be addressed soon but not necessarily immediately. The engine appears to run fine and except for the code there is no indication of a problem.
Could this simply be a sensor replacement issue and not something more serious?
Sorry to ask fundamental questions like this but I am not an experienced mechanic on this car.
Bill
92 XJS 4.0 coupe

 

As with many fault codes that appear for the first time, I tend to just reset them and see if they come back. Often you never see them again!

Another owner had this and the attached reply is here which may help you if it does come back:

https://www.jaguarforums.com/forum/x...e-ff26-181307/

Good luck

Paul

 

Thanks Paul
I did search on FF26 but nothing came up. Maybe I did not set the search up right.
Anyway, that was enough information to tell me to be careful about the issue because it has potential to cause damage.
I will try resetting and see if it recurs.
Thanks again
Bill