So just picked up my 2011 XFR (110k KMS) on Wednesday. I've driven about 300 KM'S with no issues all felt perfect. Tonight I met with a couple friends and accelerated on to HWY, then gear box fault pops up. Can wouldn't change gears and was reving high, no check engine light came on. I turned car off and back on and all was good. I drove for another 5 minutes or so and it popped up again, this time check engine light as well. Car again felt limp and wouldn't change gears. I turned it off and on and all was perfect again, until about 3 minutes later and it happened again. I then had the car towed home. I'm 3 days into ownership of my first jag and needless to say I'm not to happy. Luckily u purchased an extended aftermarket warranty in case of a big issue. The only code that we could read was p2704 with a cheap code reader, I don't know if it was picking up all the codes as I haven' had a proper scan tool on it yet. I've read everything from battey, throttle body, solenoid to transmission is toast. I won't be able to get to my jag specialist until Monday anyone have any food for thought until then? Thanks guys.

 

It's essential that the battery is fully charged and in good condition or you will get spurious faults showing. That would be the first thing to check.
Also, the batteries are only good for around 5 years before they begin to fail.
Hope you get it sorted.

 

Went for another 20 minute drive this morning and no issues at all?? Seems so strange I couldn' even drive two minutes without it happening yesterday. My jag tech was actually open today so I had car towed there. I didn' feel safe getting on HWY and having it happen again.

 

+1 Battery #1 suspect.

 

Not sure it can be the battery. When you're driving the alternator is generating power that should be plenty to run all the systems. Particularly on highway driving
My guess is that's the reason the previous owner sold the car. Have it checked by an experienced jag tech. And in parallel suggest you call the people you bought it off and say there is a major issue and you might be back in touch...

 

The car can't always run properly with bad battery and alternator as it can't get the proper peak currents for the coils.

The actual codes may help.

 

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I suspect a fault in your spacer block between the valve body and the transmission housing. You probably are losing pressure when it is hot. I would have them pull the valve body and solenoids and check everything.

 

Hey bud, had the exact same problem, at peak temperature it did that with me, at the end was a valve on the box that went wrong. The exact write up was.

'as a result of the valve body malfunction the oil pressure dropped which resulted in friction plates, rubbers, O rings and pistons overheating. which lead to oil contaminated the parts listed above.'

 

Hi, Sorry for reviving a dead post. On the other chance you are still around @Mr Sharky , may I ask how much this cost you to get diagnosed and repaired? I have a similar issue on my (new to me) XFR.

Thanks!

 

For what it's worth - I'm afraid I can't give any advice on cost, but there are usually 2 main causes to this on our car's ZF 6HP28 transmisisons: 1) Failed seals 2) Failed bushings.

To illustrate the failed seal issue, here's an image of a replacement seal kit for the transmission - you can get these everywhere on ebay etc.



First likely seal failure: The seal for the connector to the mechatronic unit, which locks into the transmission casing - this is the threaded plastic tube on the left of the image above. This has O-Rings that break down over time, and can leak - this is usually easily spotted just from crawling underneath the car and looking around the wiring connector on the rear of the transmission.

Second likely seal failure: The valvebody-to-transmision seal - there are 5 of these (the remaining seals in the image above), but the rectangular plastic one is usually the one to go - the plastic goes hard and brittle over time (much like our coolant pipes ) and then cracks under vibration/heat cycles, causing fluid to leak.

Both of these things can cause loss of fluid pressure or overheating, which can cause the issues discussed. You can actually replace all seals necessary with the car up on a lift (or even jack stands) - there are a couple of threads on the forums including one I've written that detail this.

The second problem is more serious, which is a bushing failure - the bushings inside the transmission wear out over time, meaning that when the transmission is hot the fluid can leak past the bushings causing clutch slippage etc. This is usually most obvious in the higher gears. This will require a transmission rebuild to resolve (or replacement with a good used one). However, it's worth noting that the ZF 6HP26 or 28 is a ubiquitous transmission used in BMWs, Audis, etc, so plenty of companies like Sonnax sell bushing kits like this one, but also there are plenty of transmission shops with the knowledge and tools to rebuild these units, so having the transmission rebuilt may not be cost-prohibitive or even difficult.