Emissions Workshop warning

Fairly new Jetta TDI owner. Got an 06, Auto about a year ago and now have about 73K mile on it. Have not had any significant issues with it. Got another 06, manual 5speed about 6months ago now have about 120K mile on it. About a couple months ago started getting the “[FONT=&quot]Emissions Workshop Warning” intermittently on the 5speed. It comes on at start up and then goes out. Not being a mechanic I did a couple easy logical checks. Inspected the air filter, it was clean just a little debris on the prefilter. Cleaned it and placed back in. The warning went away for a couple weeks then started intermittently coming back again. Now my other TDI, Auto is starting to intermittently have the “Emissions Workshop” warning come on. I did the same treatment with the air filter and got the same results with the “Emissions Workshop” warning going away for a little while now coming back on at start up.[/FONT]
[FONT=&quot]Thanks for any advice…[/FONT]

Not much to go on. You need to have someone check for fault codes and then after that diagnose to find the problem(s) for the fault codes found. The best time to check for codes, is when the fault is still active (light on) because some codes will self clear over time

Does the car run differently when the light is on? How old is the fuel filter? The change interval is 20K miles.

Fuel filters were changed in both within last 5k miles or so.
Neither one appear to run much different when the warning comes on.
Haven't taken it in to check the codes but I talked to a local mechanic, without taking it to the garage, and he said if there wasn't a perceptible change in how it's running it's not a big deal. He'll check it next time I bring in for maintenance.

Thoughts?

You mechanic is somewhat correct, if the car seems to run O.K. you could most likely keep driving it and not hurt anything.

It always a good idea to sort out these kind of problem because the light is telling you something is not working correctly and if something else develops a problem and sets a fault code you won't know it because the light is already on.

Have someone read the fault codes, write the actual fault codes (P12345 etc.) down and report back.