I'm still having problems starting my 2003 Jetta TDI diesel in cold weather. I just had vw check my battery & electrical system, and they said its fine, but if its 20 degrees F or less, no turnover. Its been recently suggested it might be new battery time, and vw is insisting I need to have it replaced by them, so the battery will match the alternator (?). Needless to say they want $215 to do it, when elsewhere they are 1/2 that much. I want as high a CCA rating as I can find that will fit (the alternator?)
Please advise, and thanks.

what about a cold start package with a block heater and power assist plug? Doesn't vdub offer that might want to check with blubyu he is pretty good with the vdub stuff

a battery that will fit the alternator? what the **** is that? lol... never heard of anything like that.... any battery will work as long as it has enough amperage to crank the car, i reccomend an Optima Red top battery... Its a dry cell battery made for high cranking power and abuse, will take anything you throw at it, if you have a system or anything go with the yellow top though

You can throw a battery in yourself in 5 minutes, just go to autozone and pay the 110 for an Optima battery... if you want one of them damn duralast batterys or whatever for half the price, but the dry cell is best for cold weather

Now... your problem may not even be a battery issue.... You say it happens at 20 degrees and below, maybe your car has some sort of heater that starts up first and has to warm the engine a bit first before it will let you crank it over

a battery may be a good idea anyways, they only last so long an 03's battery is about 3 years old now and is probably about ready to take a shit

You need to let the glow plugs cycle to create a hot spot in the cylinders. You try cycling them like 3 times but they are trying to screw you over. Just get a battery you like or even the factory one if you want to covers to line up and go back together correctly. But optima's work real nice, you need a yellow top for the deep cycle since turning over an 18.5:1 compression diesel motor in the cold takes A TON of juice to say the least.

What you should buy and i think every tdi should have one is a tdiheater. Its a coolant pump that warms the whole motor and puts less strain on the electrical system on start ups and less wear on cold starts. I ran one on my old tdi since it was new anytime it was below 40 degrees and it made a huge difference.

With a combonation of a yellow top or even just a new battery and a tdi heater from www.tdiheater.com you will be all set to go

Thanks blubyu. I aleady ordered one. I put up with this all winter because vw insisted nothing was wrong and had never heard of any fix, and my web research skills must suck.
I knew the vw guy was just trying to sell me his battery. Because I'm just a woman who doesn't know anything. Sure sounded like bull to me too.

Recently I HAD to get somewhere, and I just kept turning the key until the glowplug light went out. Over and over. It took 20 min (the longest I ever tried) but it did start. But WTF.

By what you said you might need some new glow plugs if it is taking that long to get the cylinders warm enough to fire. I never had to do mine more than 3 times (~5min) at that was like -5 degree weather.
http://www.tdiparts.com/catalog/product_info.php?cPath=29_90_94&products_id=501
good link for the glow plugs. Its getting time to do some mantience on the tdi so it will keep going for a long time.
What is the current milage?