came on today dont notice any difference with car or performance could it be egr valve ? any way of checking ? ta

Get the code read mate. Its the fastest, easiest and is a lot more accurate than having a guess. You can pick them up cheap enough or if you ask nicley someone on here local to you may even read them for you.

Have you got EGR delete fitted?

 

Need someone to scan car with VCDS ideally.

no egr fitted yet will do though car still goes well not noticed any difference apart from the light 

Cause could be anything engine related. Not all issues affect the running of the engine, but could affect economy for example. Getting the fault codes read is by far the quickest way of identifying the cause.