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2004 Passat Burning oil and CEL has been on


I am the unfortunate 2nd owner of a 2004 Passat. Purchased it this year with 140k on it. The CEL has been on since June (3days after I purchased it) and despite my mechanics efforts to resolve all the issues he has just given up. It has lots of codes mostly vacuum leak related. Now I am noticing the car is burning oil and the codes the car has now is a vacuum leak code and the Turbo undercharge (P0299). Here are my questions:
If my car is burning oil (not leaking) it could be worn piston rings, gasket valve cover and anything else? Could any of those also cause a vacuum leak? The P0299 code, could that be caused by a vacuum leak?

I wanna love this car, but I can’t. I’ve spent too much on it and still have to spend more on it.


Sorry, I mean to say that the car had mostly vacuum leak codes prior to my mechanic giving up. He managed to get the car running smoother but the CEL still came up.

Turbos often have all sorts of vacuum lines going to them that make them behave. It could very well be that he missed one that still causes the P0299 code.
Turbos also run with oil…
If the problems’ timing coincide as to when they started to occur, it could be a clue. Did the oil consumption and Turbo problem happen pretty much at the same time?

I wouldn’t necessarily jump all over the piston rings being the oil issue. For instance, a stuck PCV (a valve) could cause oil consumption, among other things and those things are usually easy to replace.
One would imagine your mechanic would know how to check a PCV, tho…

How do you know your car burns oil and not drops it? If you park it with a sheet of plywood or cardboard under the engine, do you see any drops of oil? The engine compartment is clean?
Any exhaust of weird color that doesn’t go away and/or gets worse when you stomp on the gas?

"Now I am noticing the car is burning oil . . .
"If my car is burning oil (not leaking) it . . . "

What evidence are you using to state that it’s burning oil ?

1 - Visible smoke at the tailpipe ? If so, When . . . idle, accelerating, cold, hot, all the time ?

2 - Engine oil level drops and oil must be added ? If so, how much oil . . . 1 quart per __ miles ?

3 - 1 &2


The 1.8 turbo that was mated with the Passats & some model Audis (I think up to 2005) was notorious for sludge buildup in the engine if the oil was not changed frequently with synthetic oil (vw approved). These models did not have a large oil sump capacity and most likely the turbo was abused by not changing the oil frequently enough. The turbos would burn up the standard non synthetic oil & drop little burned droplets into the oil pan, and these would in turn clog up the oil pickup screen (they affectionately call these ‘turbo-turds’). This would cause the engine to be starved of oil.

The PCV system would cause the vacuum codes as well, if I remember correctly.

The only thing to fix the oil problem on these was to drop the oil pan and clean the pickup screen, or replace it. If the engine & turbo is too far gone, there’s not much you can do without either replacing the engine or having it rebuilt. Not saying that this is what happened, but more likely than not, it is characteristic of many of these cars that were not maintained. There are plenty of forums online specific to Passats that will give you more info, but my guess is (unfortunately) the oil starvation is what happened.

Thank you all for your input. To answer some of the questions asked, when I purchased the car (wholesale basically) and checked the oil a couple days after I noticed it was just about bone dry, VW ran a diagnostic due to the CEL coming on as well and they just said the spark plugs had oil on them among other problems including a cracked pvc. The issue with the plugs was never really addressed since I decided to take it somewhere else. A few months later I often notice a smell of burning oil, not overly strong but I haven’t really noticed smoke or blue smoke for that matter. I also don’t see any evidence of it dripping since I park in the same spot everyday at home.

As for the turbo that code did not come up initially when the first problems came up. It was only after spending close to $1k on fixing all these leaky hoses and the pvc and I think another valve( I can’t remember which one), did the CEL come back on a day later and came back with the P0299 code and then a vacuum leak code. This was in August and I haven’t done anything else to it since.
I just started noticing the burning smell 3 weeks ago and have been checking the oil every other day and have had to put in a little more than a quart so far.

I have read in some forums about changing the N75 for the Turbo problem (again not sure what that is). My mechanic checked the Diverter Valve and found nothing wrong with it.

I predict there’s going to be an epidemic of abused turbo engines in the near future given their rising popularity plus quick lube shops filling them with low-bid conventional oil.

I’m going to go with the turbocharger.
The turbocharger is basically a shaft with an impellar on each end, one for the exhaust to spin the connecting shaft and the other supn by the shaft to pump air in. The bearingas are cooled and lubricated by the oil. In the Passat turbo drawing attached the oil runs through lines 7 and 8. If the seal on the shaft that sperates the intake airstream from the oil-fed bearings fails, you’ll not only be drawing oil into the engine (burning oil) but that will also act like a vacuum leak, especially of the seal between the exhaust side and the bearings is shot too. Exhaust will be hitting one at high pressure and the intake will be putting suction on the other end of the shaft.

Turbos operate a very high speeds, up to 200,000 rpm, and get heated by the hot exhaust. A failure of this type in a car this age is not at all uncommon.

I do not want to beat you up, but:
when I purchased the car (wholesale basically) and checked the oil a couple days after I noticed it was just about bone dry
Why did not check it before?
Any prebuy inspection happened or not?
Why did you buy this car? I am just asking, 8 year old car with unknown history, (wholesale) usually not a good sign, plus turbo plus lack of maintenance begs for a lot of money to fix…
I am sorry for you…

With an oil consumption problem you should always run a compression test. This brings up the question of why in the hxxx would a mechanic pull plugs and not check the compression while the plugs are out; even on a good running, non-oil burning motor.

The oil consumption could be both a piston ring problem and a turbocharger seal problem. My gut feeling is that the car’s odometer may show 140k miles but due to a heavy foot of the previous owner the engine may feel more like 300k miles.
They saw the writing on the wall and unloaded the car…

(I might add that manifold vacuum is affected greatly by engine wear so that’s a possibility for the various vacuum codes that exist.)

The purchase of this car is a mistake I am living everyday and a long story at that. One that could probably be settled in court if I had the means for a lawyer, but thats another subject. The car was an ebay wholesale car. I purchased it directly from the dealer saw the car in person, test drove it, saw the car history which showed an owner who seemed to have done all the right maintenance (again only going by what CarFax said). It was just my bad luck that 3 days later the car goes downhill.
Anyway, I think I am gonna give VW the honor of my $99 to give me an initial diagnostic. I was just curious to see if the problem with the oil could be related one way or another to a vacuum leak or if even the Turbo be related to a vacuum leak.
I am just a woman that knows a little bit more about cars than your average woman. I’d love to be able to fix my own cars if I had the tools and space for it. But with every car problem I have encounered in my years I just learn a little bit more about cars, thats the only plus side of it

Thank you all again

At this point I would suggest you to find a good independent VW mechanic and have a complete evaluation done. He or she could compile a to do list and prioritize what can be and should be done brand what order. Could give you an idea what needs to be fixed asap and what can wait.
Good luck.


Have you had other CEL’s? What # were they?