[fester]

I'm going to have a guess here and say it's not from the Jeep dealer as they would have surely at least cleared the error before letting the car get tested if nothing else. I wonder if the code magically appeared the moment RACQ got their hands on it, who in their right mind would put it up for sale with an active check engine light.

This issue could be as simple as fluid level, low or high, or as major as near complete meltdown and only the Jeep dealer or a very good trans shop with Merc gearbox diagnostics will be able to track it down. They need to be able to read the TCM, the ECU codes for gearbox issues are near useless. Having said that these gearboxes are actually very robust and not much goes wrong with them , they are powering millions of Merc from the family sedan to high power V8's.

I would want to know who is repairing the box and I don't have a lot of faith in the local Noosa Jeep dealer. AT any rate I think I'd be walking the other way from a dealer that puts a car on the lot with the CEL on. I'd also be reading the warranty carefully first too.