I have a 2000 XJ Classic. Every so often while driving the engine light and air bag light will come on and all the gauges, including the speedometer, will drop to zero. Eventually they will return to normal with no change to vehicle performance whether the gauges are working or not. About had a hart attack when it first happened when I saw the engine light come on and no oil pressure. Felt better after determining that I did have oil pressure and it was just the gauges. Any assistance as to what is going on would be appreciated.

 

Search for "loose connection at gauge cluster" or "no gauges" with the search function, you'll have your answer.

 

X2
I have the same problem and it is a loose or dirty connection. When my gauges drop out I just give it a light hit above the the gauges and they come back on.