Hi all.
I own an 04 XJ8 SE and have been getting the following messages;
Air Suspension Fault.
Gearbox Fault.
Check Engine light amber.
All of the above mentioned have been displayed over about a four week period at one time or another. They disappear of their own accord so I couldn't understand what was going on. The car runs fine and all looks OK. However, I suspected that the battery may be at fault at first but then I altered the way I start the car. What I now do is insert the ignition key, let the seat and stearing wheel adjust automatically, then start the engine. Hey presto, since doing this I have had no messages at all so I suspect that starting the engine whilst the seat and stearing wheel are moving causes such a drop in voltage that it fools the car into thinking it has a fault.
Anyone else had the same?
Happy motoring. Les.

sounds about right.. and check to see if you have any water in the trunk

This could absolutely explain my Air Suspension Fault message as my dealer tech did not find anything wrong with the suspension system and gave the car back to me without touching it (except that they did fix an air bag problem which was apparently a lot more serious than I thought it was). I'll have to give your method a try and see if anything happens for the next few weeks.

But what I wonder (really) if what this really means is that we need new batteries?

What does it mean if there's water in the trunk?

It sloshes around and corrodes electric wiring connectors and any electronic assemblies that get soaked. Earth points also get degraded and cease to earth properly.

Agreed Fraser. Belawidi, here's the bulletin that identifies the possible entry points. Always worth checking to ensure it's unrelated to electrical gremlins.

I'll look into it and let you know the outcome. Thanks again.