My jag is in limp home mode. No one around me seems to have any capability to "talk" to the car's computer to find out what is wrong. Does anyone have any suggestions. Really appreciate any help.

 

Is the check engine light coming on.

If so then the trip computer should display a fault code briefly when ignition is switched on , before starting the engine.

FF followed by two digits

Is this showing ?

 

The check engine light came on last summer off and on and showed the fault of FF67.

It is not showing check engine this time. No one around here could tell me what FF67 meant. Any help much appreciated.

 

Hi Roni,

If check engine light not on it could have been an intermittent fault.

FF67 is a fault associated with air injection pump.

This device is not fitted in all markets where XJS V12 was supplied.

It's part of emission control system:

Lambda sensor control fuel air mixture and hence exhaust emissions. They take a short time to get up to working temperature (heated by exhaust gas and electrical heater)
Air pump is used to inject air into exhaust to speed up this warm up of sensor.
Pump is driven by belt from engine via a clutch, it only operates for 45 seconds after engine start.

My engine not fitted with the system, many who did have it fitted choose to remove it.

 

Thanks, I'll pass along to my mechanic. He seems to think the problem has morphed into something else (or something else is wrong), but happy to try anything at this point!

 

FF67 can often be fixed by replacing the air injection check valves at the back if the engine bay. I believe they are standard GM parts from when I changed them. Just match up the thread size and hose nipple size.