Emission control system failure light

[jbbkt91]

Hi all I previously posted a thread about my engine management light coming on after a wheel tyre change but have just found out it's the emission control system failure, hers my previous post with the details:-

"Engine management light on after putting new wheels/tyres on
Hi all,

I have a 2003 a6 avant 2.5tdi quattro. Fitted were 17" alloys but because I live in a very snowy area I recently replaced the alloys with 16" steel wheels and hankook snow tyres. About 10 minutes after driving away the engine management light came on. I was on the motorway and needed to get home. The next day I drove the car and the light came on, stayed on an then after approximately 10/15 mins the light went off and stayed off. Then today I used the car again the light again came back on. I have read on another site that it could be to do with tyre pressures or the wheel size not being recognised but the person wasn't too sure. Does anyone have any ideas?"

As I say it's not the engine management but the other details are correct.

Thanks in advance if anyone as any ideas as to why these 2 things maybe linked.

[tinbum]

Cant say its the same as yours but had an intermittent light which eventually turned into a full time light.
Diagnosed a problem with the EGR system which i traced to a faulty solenoid vacuum valve (N75). Main clue was no vac being pulled wheh tube disconnected fron the EGR valve with engine running on cold startup, also evidenced by cross link manifold staying cold on start up from cold.
Sourced a new one, fitted,within 3 engine starts light is now off.
Hope this is of some help.