limp mode no power help

[widget2k13]

hi, after years of trouble free motoring in my little a2 it has now decided to go into limp mode now and then, normally after the car has been running and done a few mile it loses all power.
turning the ignition off and on resets it and it works a little bit then goes again so i presume its in limp mode.
vag com shows code 17964, i have researched and found loads of different solutions, i have checked all the air pipes i can see and seem fine visually, the egr valve looks quite oily, there was a little oil around the pipe that goes into the throttle body and held in with a big clip.
i was reading about the n75 valve but mine doesn't seem to have one on the nearside near the header bottle ?
ive ordered a new fuel filter to start with the cheapest option.
any ideas what it could be or just go through everything i can find on the forums?

 

[Guest 4123]

The 'tell tale' sign all is not OK with this sensor is if the water temp gauge no longer goes to 90 C when the thermostat opens and stays there, or the needle behaves erratically. I believe there's possibly a logic loop somewhere in the system that compares the two signals and if they don't match may switch the engine control to 'limp' mode. Erling (the real 'elder). #5N007503

I'm not sure that's true Erling, because there was someone recently complaining that their calculated fuel consumption was too high. This was because the second sensor is used by the instruments and calculates fuel consumption; in his case the second sensor was under-reading. In your case, perhaps the first sensor failed completely, which caused limp mode?

PS You should encourage your son to get his own account. I was beginning to think that you were younger than your son!

RAB