Hey everyone,

I have a 1998 XJR that has been largely trouble free in my two years of ownership. Lately, every once in awhile when I tart the car from cold it will show the "Engine Failsafe Mode" warning with an amber light AND the check engine light will come on. When this happens the engine failsafe mode warning will go away when I activate the throttle as I drive the car. I hit the throttle and it goes away, I get off the throttle and it comes back. The check engine light stays on the whole time. Car runs normal during this time. I can't even feel the normal reduction in power that comes with the failsafe mode, but I am driving slowly in an urban environment so I might just be missing it. Any thoughts on causes? I haven't been able to get the code read because it happens unpredictably and I haven't been by a auto parts store or dealer.

 

If the CEL stays on then codes have been stored. We need you to get the codes read and post them. That will give us a place to start.
Also make sure to get the battery load tested. A dodgy battery gives off all kinds of false conditions. I would suspect the battery is the bad guy in this. When you start the vehicle cold the battery voltage drops and causes the alarms. Once the throttle is brought up the alternator replenishes the battery, the problem is the battery most likely isn't holding.

 

I seldom drive my 1999 XJ8 and when I start the engine after sitting for a few weeks, the display flashes ASC/Traction Control, Restricted Performance, Check Rear Lights, etc.

I charge the battery to keep it up if I don't plan on driving for a while but I know what the problem is so I am not concerned that there is an actual fault.

Computers/modules DON'T LIKE LOW VOLTAGE!!!!!!!!!!!!!!!!!!!!!

bob