2001 ALH w/ P0402 Excessive EGR Flow

I recently had a Check Engine light (P0402 Excessive EGR Flow) come on. Pulled covers and air box out of the way when I found a disconnected vacuum line. Unfortunately, I can't find where it gets its vacuum. There is no audible sucking sound and the car runs just fine...any ideas?
I have a picture I took with my phone, but I don't know how to paste it into the body of this post...

2001 Jetta, if that makes any significant difference.

You must copy the data upload at pics.tdiclub.com (log in again) and harvest a link.
Try this for hose routing

BobnOH, I found where the line was supposed to hook in to the air box. Thanks for the help! I decided to check the EGR Valve for cleanliness. I was shocked to see just how filthy it and the intake were! I did a full intake removal and clean out. I made a block-off plate on the exhaust manifold, but left all of the components on the car in case I need to make it emissions compliant later. The CEL continues to come on with the P0402 Excessive EGR flow. How is this even possible considering there is no exhaust flow into the EGR system. Is there a potential for an electric issue? If so, any suggestions? I am still getting around 40 MPG in town and 46-48 on the Interstate, so I have no real complaints aside for the annoying CEL on the dash...

The ECU would need to be reprogrammed to kill the CEL. Fact of life.

I'd note, however, that just because you found the EGR valve and intake to be gunked up that doesn't mean that it would promptly gunk up again. Consider that it's a 16 year-old car and that it might have never been cleaned before. I cleaned the wife's car at about 155k miles; though it was gunky, performance was still really good; so, that would be at least six years before the car would approach this number of miles (at our driving rates), and I will wager that it will NOT be as gunky as it was the initial time- reason being is that we're running better oil (than was available in earlier years), we're driving our cars highway miles (get up to temp and get exercised well) AND our tunes back off the EGR (not deleted, just relaxed).

Oh yeah, we average over 50mpg (have three of the same cars, with EGR- all average over 50mpg).

Bottom line: I'll never have to clean the EGR valve and intake again, even though I am still running with EGR valve (and cooler).

Tankthecarman said:

The CEL continues to come on with the P0402 Excessive EGR flow. How is this even possible considering there is no exhaust flow into the EGR system.

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Check your MAF sensor. If your MAF numbers are too low, the car says, hey, I must have excessive EGR flow. However, if you've disabled your EGR, it's now going to skew your MAF readings in the opposite direction. Regardless, check your MAF.

For whatever reason, when the EGR valve is NOT working properly, the ECU sees the MAF value too high (which is normal) but it incorrectly interprets the DTC as "excessive EGR flow" when in fact it is "excessive MAF flow", which is due to an inoperable EGR.

I think something just got lost in translation. In any event, you have an EGR problem. Super simple system. Vacuum actuator on EGR valve, controlled by a duty cycled solenoid allowing vacuum to that actuator. If there is no DTC for an electrical problem with the solenoid (the N18), then you know the wires to it and its connection is sound. If the turbocharger is working, then you know your vacuum source is sound, and chances are there are no leaks in the vacuum system, as those are usually manifested as low/no boost problems before EGR problems.

So it *could* be a clog in the vacuum line to the N18 specifically, or a clog in the line to the EGR valve (doubtful), or (more likely) just a bad EGR valve... specifically the diaphragm in the valve is no longer able to hold vacuum thus the EGR valve can no longer open.

In less time than it takes to read this post, you could check the EGR valve.