Continued 996 Tiptronic issues.

Hi Folks. I bought my 2001 996 C4 Tiptronic with 88k about 6 weeks weeks ago with an undisclosed Gearbox issue. I won't go into the circs as to how I bought this lemon, but i'm still trying to get the gearbox working. The box goes into R, 1 and 2, but then won't go into 3, 4 or 5. If in auto, it selects 1st and then 2nd and when ready for 3rd, just revs with no drive. If in manual, it selects 1st and 2nd, but revs when you select 3rd. It pulls nicely in the gears it will select, no odd noisy that I can tell or anything untowards. Sometimes it is accompanied by flashing D and 4 on the dash and the 'engine check' light, other times not. I have tried the following: 1. New battery. The car came with a flat battery, the new battery didn't change the gearbox issue, so possibly not a low voltage issue. 2. Disconnecting the battery for 30 minutes as some have suggested. Made no difference. 3. Reading the codes. My Autel doesn't have Porsche software, but my brother came over with his £12 scanner and found two codes relating to (i can't remember the exact wording) **3 speed mismatch and **4 speed mismatch. Like i've said, I can't remember the exact code or wording. The faults were cleared but to no avail. 4. I have serviced the Transmission and fitted new Porsche Filter and Fluid, following the exact refill procedure, still the exact same issue. The magnets in the bottom of the sump weren't overly fury. The fluid was black and disgusting, but I got about 4.5 litres out 5. I borrowed a more advanced reader, and found the following (Launch X431 scanner): -73 inactive. Gear Monitoring, 3rd Gear. -74 inactive. Gear Sel. Monitor, 4th Gear. These were cleared but still the problem remains, but no codes are showing when re-scanned. Now whilst I had the scanner, i Observed the following whilst looking at the switch data on the device.. If I selected R, R would show on the reader. If i selected N, N would appear, and likewise for D and P, the demand was echoed on the reader. If I went into Manual, the reader still showed the car to be in D, so could this be a clue? At this point I started watching the dash display to see what that was doing and observed the following, by this point the engine and box were well up to temp: If I selected P through to D, the display would show D 1 as i'd expect, if I went to M, it would display M 1. Now if I went back to D, it would display D 2, suggesting it had selected 2nd gear. If I went back to M, it would select M 2. Back to D and it would select D 2. This seems to only happen once the engine and box were nice and warm. Still no fault code and the gearbox fault still persists, but are there any clues here as to what the issue could be? I have read a few forums and people have mentioned how easily does the gear selector move. Well, I've never driven another 996, but would say its fairly stiff between the different positions on the Auto shifter. Any other suggestions for what to do next? I feel pretty comfortable if I had to drop the gearbox sump again. I can't just drive it to my local Porsche dealer to be looked at as it'll only drive in 1st and 2nd, so would need recovery. I can't help but feel it'll be something like a switch or solenoid, but I don't know which. The car isn't the nicest, so I don't want to spend £0000's on it as I don't think the value is there for this particular car. I've wanted a 911 for years but am now pondering just selling it as it and cutting my loses as i'm so disappointed with it. Thanks for reading.

The tip boxes set off in 2nd gear in drive anyway - programmed like that, so that's maybe why it can initially go in to D2. I don't know much about the tip boxes, but isn't there something about the oil not being right in them that causes shifting problems? Also, there's an electronic gear selector on them that could be faulty. But after a quick root around on the web, could be various electrical components in there. Read this, might help you:

It could be a problem with the internal wiring loom that connects the solenoids or one of the solenoids not working, i think you can buy all of them with the loom on Ali express or the other Chinese web site for about £60 might be worth a punt changing them. Or take the solenoids somewhere to be tested and test the wiring for continuity. Check all the wiring and the plugs on the side of the gearbox as the little pins inside can be bent and not engage properly with each other. Also the multi switch selector on the side of the gearbox can start to separate as the rivets that hold it together rot and the contacts inside don't fully engage it's worth checking . or it could be faulty. The shifter cable must be correctly adjusted in perfect harmony with the shifter and the selector, any overlap into another gears position will cause mayhem, so each gear position on the gearbox including neutral and park should light up on the dash in tally with each other. At 88k miles the mechanics in that box should be fine so if it's not any of the above it could be a problem with the TCU.

Disconnecting your battery for half an hour should have reset the TCM so look at clutch bands or gear change solenoids… of course the vendor will likely know exactly what the problem is, whilst he will be aware that you aren’t happy with him you now have nothing to gain by not asking him for information?

I wouldn’t write the box off yet, but I also wouldn’t keep guessing. The useful insight that it drives properly in reverse, 1st and 2nd, then loses drive when it asks for 3rd. The gear monitoring faults suggest the TCU is commanding a gear but not seeing the shaft speeds it expects, so something is not applying properly. Start with the easy external checks first: selector cable adjustment, the multi-function/range switch on the side of the gearbox, gearbox plug/pins and wiring. If the shifter is stiff or the selector/range switch is slightly out of line, it can cause strange behaviour. If that all checks out, then I’d drop the sump again and look at the internal loom and solenoids. A wiring break or lazy solenoid could explain why 1st and 2nd work but the higher gears don’t. However the black fluid you are seeing means there is still a chance the box has internal wear, but at 88k I’d prove the selector, range switch, wiring and solenoids before assuming the worst. Keep it methodical or it’ll turn into an expensive guessing game.

Is that your car on FB marketplace, or the seller you bought it from? Only ask as I saw the ad with the same issues you described

Quotes source post: 2801551

It’s mine buddy, my advert also.

That’s cheap! hopefully you can sort the issue

Have you rechecked the transmission fluid level since replacing? I completed a gearbox service on mine by following the procedures to a T; however, upon test driving it had a head fit so I checked the level again and almost another litre went in!