[Britwrench]

The TDI needs running on a VW tester and the report printed out.

If there are numbers out of the accepted range, further diagnosis is called for.

Have a Jetta TDI that the light comes on intermittently, it's from the glow-plug system.
There is a update kit to allegedly fix this problem.

These cars also suffer from build up in the intake manifold causing starting and idling issues.

Need way more information before any diagnosis can be made on what the next step would be.

Look at the TDI club website.