Oh yeah, that’s what I’m talking about!

VW TDI Mass Air-Flow Sensor assembly

My car has been running poorly of late. Nothing serious, just not feeling like it should. A bit of power loss, really. But mostly the symptom I noted was crappy fuel economy. Mind you, what I consider “crappy” most people would kill for: 43-46 MPG. That is way off the usual 50 MPG that my TDI routinely delivers.

On the NWBioDiesel network discussion mailing list the subject of dirty EGR valves came up and “Dr. Dan” of Dr. Dan’s BioDiesel in Seattle noted the following:

As far as I can tell if the mass air flow meter is healthy the intake will not plug up!!!! There is an updated part that works better than the original for 1999 to 2004 ALH motor (non PD) # 0281 002 757. This is one of the most important sensors of the engine, it effects power, mileage, emissions and can cause the intake to plug up with excess egr. When we change an air filter we look to see if the car still has the old style MAS if it does we look in the intake to see how plugged it is, if it is starting to plug up we test install a new MAS. If the car runs better we leave it on and that seems to stop the intake from plugging up more. If your car has the other older MAS it could be smart to replace it with the new part.

I figured this may have been the cause of my clogged ECR & Intake last winter, so I called my local VW breaker and asked for part #0281 002 757. They had one so I told them to set it aside for me. Once home it took all of 3 minutes to swap the part: two phillips head screws and one plier-operated hose clamp. The transformation is amazing!

It is like I have my old car back. No power loss (mind you 90HP isn’t a lot of power to start with, but I digress) but best of all, my first half-tank since the swap:


367 miles on exactly 7 gallons of fuel.

Oh yeah. 52.4 MPG. That’s all on home-brew BioDiesel and my normal driving style, which is kindly described as… lead footed. Once the warm weather comes back in earnest I’ll have a go at HM’ing my way to max-MPG and report here.

If you have a pre-Pump Duese TDI and your MPG has fallen off and the car seems a bit sluggish, try swapping this MAS in (and clean your EGR & Intake) and see what happens. You’ll be a happy TDI owner again!