Audi A3 start/stop system fault

[Traser13]

Hi Folks, i've got a fault appearing on my start/stop system. The search function shows other members have had similar problems but I've not been able to find a solution. the car is an Audi A3 2.0TDi Quattro 61 plate with 65k. Last work done on it was anew EGR valve and cooler last summer.

Last week the car came up with a error on the digital display reading "start-stop system, system fault! Currently unavailable", there is no warning light though. It's been below 8*C in Scotland but the car had just been on a long run and had been up to temp for about 30 minutes on the dual carriageway.

My garage found a P15A100 code. Described as "Neutral position sensor, implausible signal". The sensor has been replaced and the battery checked - the code has gone out of the system. The problem seems to be sorted but the garage say the start-stop fault on the dash is still there. The diagnostics guys said it's probably just because of the cold and it should go away in the spring . . .

Any ideas why the fault message on the dash isn't clearing?

UPDATE: I've just take it for a drive & the car is getting up to temperate. The start stop fault message does not come up immediately. First stop it come up and shows the start/stop is deactivated as normal. After about 15 miles I stopped and turned the car off/on (& removed the key). The fault does not come up immediately, the car is up to temp and lights, heater etc were all off. The start/stop still shows as deactivated at the next stop but the fault returns after that.

Here are the faults:

This one is now gone.
Audi fault code.jpg

This one won't go away.
Audi fault.jpg

[Traser13]

Looks like the neutral position selector in the gearbox has sheared off. Audi recommend a new gearbox.