I was wondering if anyone has any insite into a problem I am having.
After driving from LA to Orange County...using the usual Tiptronic functionality (at proper revs). All of a sudden at the end of the exit ramp at my destination at 4 MPH the Instrument display flashed "Pre-Safe Disabled" and I was now in "Limp Home Mode" stuck in first gear. Fortunately I only had to go a mile to get home. When I turned the car off it said 1 Malfunction.
Of course the next day the car worked perfectly and had no Malfunction in the display anymore and the car drove as if nothing had happend.
( a little back ground...2 months ago I had a check engine light came on coming down out of the mountains 7000ft alt. which also when away. And on a seperate occassion when I had to quikly release the gas pedal after kicking it down a gear or two (not using Tiptronic) due to traffic...I got a Clunk from the Tranny on the re-equalization. )
I took it to the dealer under ELW and after full investigation we found no codes related to the Tranny but did find an O2 sensor code which showed (after testing) that the 2 front O2 sensors where "Lazy" and where replaced under the ELW.
My 2 questions are:
-Is it possible for such an explicit dash warning and an actual Limp Home Mode event not to trigger any Codes.
-Could the bad O2 sensors actually cause a casscading event through to the proper functioning of the Tranny.
Not ignoring you; just haven't seen this particular problem before, and I don't know that either point below will explain the problem.
I have seen the Tiptronic become stuck in a gear - it happened to me once when I shut down without returning the lever to the normal automatic shift slot. Re-starting, shutting down, then moving the lever out of Tiptronic cured the problem (as I recall; it was 7 years ago).
Also, unusual electronic "glitches" that go away after restart are sometimes caused by a failing battery. You might want to check yours. There are some battery troubleshooting links in the W220 S-Class Owners Start Here sticky at the top of the W220 forum.