996 turbo Tiptronic fault

[minny]

This morning, the car's Tiptronic box went into limp mode flashing 4 and D alternately when changing from 2nd to 3rd at about 4000 rpm. I stopped the car and turned it off then back on. When I put it in D to drive off the lights were behaving normally but there was a definite jolt when I put it in D. Light on dash shows 2nd gear but gearbox is in 1st. It wouldn't change in auto mode nor will it change up using the steering wheel buttons. Interestingly, when I change down, the dash light drops to 1st but the box changes up to 2nd gear. On the PST2 and PIWIS, the ECU fast code is P0715 Tipronic (supply voltage, speed sensors) and Tiptronic fault codes are 12 Rpm Sensor n2(or sensor supply interrupted) and 14 Speed comparison between n2 and n3 implausible. I have cleared the codes and reset the adaptation values but the problem persists. It jolts whenever I put it in D or R so I am not going to use it till someone has a look at it. Thankfully i only had to drive half a mile home from when the fault occurred. Indy is coming with a trailer on Monday to pick it up.

Car was running 100% prior to that and it has 72000 miles. The Tiptronic box fluid has been changed twice since I owned it from 2010 and there are no leaks below. I just wanted to get an idea what I am looking at. Other forums mention the speed sensor or conductor plate.

 

[Richard_Hamilton]

From the attached diagnostic sheets, it appears to me like it is a wiring problem or a speed sensor failure. However, I would start by checking the ATF level. It might be worth checking the plug connection to the box, in case it is a bad connection there. If it is a speed sensor, the diagnostic sheet says you have to change the whole valve block (at about £1500).

Download

 

[minny]

Thank you. I did wonder about the electrical connection especially with the recent wet weather although I did avoid any puddles. Another worry is mice chewing the wires. I’ll have a quick look tomorrow and if nothing untoward, the Indy is coming to trailer the car on Monday.

 

[minny]

To update the forum, my car is fixed and the only thing replaced was fluid and filter. The problem above was caused by a corroded wire in the loom going into box so the indy repaired it.