Good day all,

My XJR has put up the dreaded gearbox fault message twice now, but drives just fine with the message on. It does not stick in gear, and the power still there, so no Restricted Performance.

MY cheap OBD reader says pending P1797, but I don't trust it to read transmission codes.

I've read lots of threads, but most are XJ8s with a different transmission, and all seem to have have symptoms when the message is on, where mine does not!

Ideas?

 

What is P1797 in english?

Fluid level?

The transmission wiring is known to wick ATF up the harness into the TCM
if the sleeve at the right front of the transmission just above the pan leaks.
It is a common fix. Your Mercedes dealer will have the improved sleeve and
seal that is supposed to be better. Not expensive. Under $50 for sure.

You can check for the wicking at both ends of the harness.

Getting a IDS system from ebay might be a good idea. You can then
read every code that the car puts out just like the dealer. It'll take
three or so weeks to arrive from Asia. About $80.

 

Thanks Plums.Do you have a model number for that reader?

1797 is a CAN bus problem. I did a hard reset, removed the engine and transmission ECUs, and cleaned all connectors and pins. So far so good. I have a road trip to Seattle tomorrow so that ought to be a good test.

 

i Think my Xjr threw the same code when the trans connector started leaking on the transmission. Very common for a 722.6; very easy to fix $10-15 part. Get a OEM mercedes part Not an aftermarket one; i have found the aftermarket ones can still leak/not fit perfectly. If you don't drain the pan fluid will drain out of the plug; perfect time for a trans service.

For more information

Mercedes-Benz 722.6 Transmission FAQ - Mercedes-Benz Forum

Part on parts geek
00 2000 Mercedes E55 AMG Automatic Transmission Plug Adapter - Transmission - APA/URO Parts, Beck Arnley, Dorman, Original Equipment, Replacement - PartsGeek

 

It's the Mongoose clone everyone talks about.

Search MONGOOSE JLR to find them.

If it's near $400, it would be the real one. Good unit
but expensive compared to $80 for hardware and software.

 

Thanks for the info, guys. So far she is behaving, fingers crossed!