W210 E230 1997 with 772.6 AT Locked in 3 gear

[yelreppa]

I am in Australia and have a W210 e230 WITH A 722.6 at. iT HAS DECIDED TO START HOLDING IN 3 GEAR ( I THINK ITS 3RD BUT NOT ENTIRELY SURE. ) However I checked the AT fluid level and put 100ml of oil in as it was a bit low. Then I test drived the car and the transmission worked without fault. The about 2 days later it got stuck in 3 rd gear again and would not change. I can move the gear selector to Park and Neuteral and through all positions of the lever without any friction. But when I initially put car into D in thumps into a gear and if I move the selector lever ro any other gear position there is no down changing or up changing. the gear change selector module may be faulty as watched on several Utube clips where the module was replaced. I also have an icarsoft V3 MB Scanner which brings up a fault code when scanning the Transmission control unit that says "Resistance is TOO Low - Selector Lever Coding is Occasionally invalid" Do you think this may be referring to the Gear Selector Module or the Transmission Control Unit in the gearbox. My email is tiffy106@ozemail.com.au if you could reply with your thoughts I would be very appreciative. Look forwaed to hearing from you soon. Cheerz Stuart

[Ivanerrol]

The transmission has gone into limp home mode. - 2nd gear only.

There a lots of reasons for transmission going into limp home - including engine faults

The gear selector module is under the shift lever and is very susceptible to fluid ingress from various drinks - coffee - sugary sift drinks etc. There's a reason there's no cup holders near the transmission lever.
The T.C.M inside the transmission can be rebuilt.

I'd suggest taking then car to an independent Mercedes specialist for a through diagnosis before spending any significant sum on it.- e.g. F.W. Graunke is near Ferntree gully.

Your main issue being - W210's aren't especially price competitive compared to repair costs.