2002 Jaguar XJ8 8 cylinder 4.0 shift by self after driving a little or a lot no pattern

(You can drive all the way to the shore with no problem or you can drive around the block every once in awhile you have to get out disconnect battery positive cable put back on the car is fine doesn’t happen all the time I drive it like that.over disconnected it goes right back to the right gears like I said if you driving all the way to Shore and it’ll happen or you can go around the corner could happen I drove it to shore many times.) This is the owner speaking …I am looking to buy this Jag…But I will like some info. from you guys to see if is expensive fix or something simple …The car drives fine till the car stat to shift by self till you disconnect the battery to reset…Mechanic told the onwer is a glitch in the computer?? Any help will be appreciated …

Hi Wrong forum this needs to be in the X300 area.

Your car will have an OBD2 port to connect a scanner. Get the code(s) and go onto YouTube. Pete

Hi Pete I am not in possession of the car yet.Let me ask the owner if he knows the code.

How many miles on the car………

A common problem is the gearbox mount loses it effectiveness and allows the gearbox to move excessively. This movement can stretch or break the wires or damage the pins in the cable on the side of the box.

Gary is correct as the pins corrode from dirty and rain and the ground usually loose.
BUT How many miles are on the car……
If it 100,001 its a ticking time bomb.
Those transmissions had 100,000 miles shelf life.

180,000 miles .Looks like I better stay away from this one. I have 94 XJ 12. I like to get a inline 6 or a v8 for family traveling.

IMHO, You can get a rebuilt transmission for cheap, BUT IMHO a 308 with that many miles even for cheap will become a money pit
Timing chains, fuel pumps, abs and traction control all become big issues.
Keep the v12 till it or you dies…….
Last of the greats. if you want a x300 get the lowest mile one you can find.
The cost is worth it, your good for 250,000 to 300,000 with the aj16 motor with oil changes!

Thanks guys

Have a great day

Hi how is the 94 Trans. same issue after 100,k ???

1994 Jaguar XJ6 Vanden Plas Sedan 4D

Different box…….old school in that xj6 .The v12 is essential an old turbo gm400 , bullet proof.
The newer cars are throttle by wire and a lot more computer.
If your is the last xj40 not 300 If I remember you still had a vacuum module

Mr Limongelli thanks for the quick response, so I should be safe with the 94 xj6…I like the style P/S I am keeping the 94 XJ12…

Thanks again

An xj40 had its issues but………any xj12 was carefuly put together and had a lot better quality parts.

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The ‘94 will have the 4hp24 trans behind the AJ16 in it surely?

I ended up getting a 2006 XJ8 Vandem Plus with 150K miles. It is beautiful in and out. $2K purchase. But has an air shock issue with the front driver side. It use to hold the pressure but now it became worse. I’m trying to move the car to get it back to my place. Anything to look at with the shocks? Looks like as the weather condition got colder, it lost more pressure, as per the previous owner.


Sabatino………this car is by itself compared to the 94 or 2001
The air ride suspension was and is TERRIBLE.
There are mini computers and a whole host of things.
If you LOVE this car…….INSTALL the coil over replacement kit for around 2,000 installed maybe more now.
It gets rid or everything airbag!
Enjoy the air bag ride…

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I am working on my 2006 xj8 that I purchased. I am having the cel for p0414. The pump works, and I don’t seem to have any air leaks after visually inspecting the lines.

Does anyone know if the vaccuum should remain after I turn off the car after the check valve? I am measuring it, and one I turn off the car it goes away.