jaguar xj6 x350 3litre petrol 2003 model.
my car started to not be able to decide what gear it should be in at about 40 mph about 8/9 weeks ago and today out the blue i went to put it in gear and heard an almighty clunk then drove off in limp mode with gear box fault in the dash, luckily only a mile from home so got it home ok , went to put it in reverse and a big clunk again,
is this a sign that it needs the fluid and filter and pan replacing or something more serious , car has done 75000 miles
would appreciate any feedback

 

Mine got really clunky when the fluid got low when the cooler lines sprung a leak. I'd get the fluid changed out and fix any leaks you may have. The lines have a tendency to leak slowly so you might not notice it unless you check the lines directly for dampness. Mine barely left a small puddle on the ground when I first noticed it and by that time it was 2-3 quarts low.

 

so this morning got in the car and everything is fine, went in to gear nice and smooth and performed as it should on test drive, gearbox fault still on the dash and eml on but no symptoms of a problem , sdd suggested transmission flash but also told me that i already had the lataest one installed so i didnt bother, at least the gearbox isnt knackered , i think its time for new oil pan and fluid .complicated precedure so gonna try and find a reputable indie to do it here in lincolnshire as local jaguar dealer is mega expensive

 

You need to get the fault codes read and interpreted. Not long after I owned the car, I got something similar to yours, and a transmission reflash cured the problem. AFAIK, the software settings can be adjusted where excessive pressures are being generated in the valving due to slight wear. In addition, if the box has never been touched, there is the likelihood of oil contamination of the contacts where the line to the TCM goes in the gearbox. There is a seal that was upgraded on later cars.

 

the only dtc im getting is p0610, something to do with the ecm i think

 

The warnings such as Gearbox Fault have proprietary Jaguar codes that a standard reader can't receive.

 

Is there a part number this improved seal? Thanks...

 

Thectsc.com has it. They show the difference in color of the seals on the electronic sleeve.

 

Looks like PITA to change...