Car Woes: They say Go to the Dealer

July 29, 2010 5:53 PM

While my pretty well maintained 2000 Passat wagon would probably pass an emissions test it can't because the computer (ECU) is failing. My local euro car mechanic and two different smog techs have had the same results: car doesn't communicate with OBD. They all suggest I take it to the VW dealer.

Here's the rub; Unless the dealer has a magic fix for this I can't afford the replacement of the ECU, it's $1200 plus labor.

The DMV will only give me an extension on my registration if I've spent $400 on smog related repairs. The car doesn't need any repairs other than the $1200 ECU. While I've paid for the registration, I'm pretty stuck because I can't afford any other repairs or parts right now.

I'm feeling very pinched in this situation and maybe my frustration is keeping me from thinking this through properly.

Should I pay $100 for the dealer to tell me what I already know?

Should I continue to drive with expired tags while saving money for the new ECU?

Should I ask my mechanic to write me up for $400 that I didn't really spend?

Any advice or reassurance are greatly appreciated. Thanks!

posted by snsranch to Travel & Transportation (10 answers total)

IANYL, and I don't know how intolerable your other options are, but my guess is that submitting fraudulent registration paperwork (by having your mechanic forge a $400 receipt) is a crime with a much more severe punishment than driving on expired tags.
posted by willbaude at 6:16 PM on July 29, 2010

Have you considered doing it yourself? Quick google search...

ECUs are not the greatest thing to buy used but they're a lot cheaper than new. You'd just to be sure you absolutely get the exact right one for your car. You should also be able to find a local wrecking yard with one out of a car which has been totaled.
posted by maxwelton at 6:25 PM on July 29, 2010

$1200 is CRAZY. Ask around in the passatworld.com forums. A used ECU will run you less than $200 and used is the way to go. They don't really "wear out" and replacement is simple.
posted by pjaust at 6:30 PM on July 29, 2010

P.S. If you want to do this yourself, mefi mail me and I'll track down good instructions for you. It's about 5 bolts that need to come out and no one should be charging you more than a half hour labor to do it.
posted by pjaust at 6:35 PM on July 29, 2010

Since they only had two engine types and made that generation for about 4 years, it should be pretty easy to find parts in a junk/salavage yard.
The people at passatworld should be able to give some guidance.
posted by ijoyner at 6:44 PM on July 29, 2010

Many, but not all, junkyards have a pretty good return policy for stuff like that. The ones that won't take the bad ones back tend to sell them wicked cheap.
posted by gally99 at 7:03 PM on July 29, 2010

This is a really common problem. There's nothing wrong with the ECU. What happens is that the ABS (Anti Lock Brake) control module suffers a failure and, since it's networked with the rest of the computers in the car, it pulls down the whole data bus. You can reliably disconnect the ABS module and regain access to the Engine ECU.
It's such a common problem that the dealers sell a revised repair kit. You used to have to buy the electronic control unit and the hydraulic pump and valve block as a whole, but now the ABS computer is replaceable separately.
As a professional tech, I have seen this happen on a number of VW and Audis and have performed this repair several times.

Don't waste your money on an ENGINE ECU because, more likely than not, it won't fix your problem.

You also don't need ABS to pass emissions. Take the car back to the station and tell them to try unplugging the ABS module and run the test again.
posted by Jon-o at 7:56 PM on July 29, 2010

Or you could just unplug the ABS module yourself and take it back. It should be on the driver's side of the engine bay, if I remember correctly. It'll have four steel hydraulic lines connected to an aluminum block and there'll be a big wiring harness attached to it. Faintly inscribed in the aluminum block will be the word BOSCH and the Bosch logo. Here's a link that has a picture of what you're looking for.
The unit has a special connector. At one end, there's sort of a T handle. As you pull that out, parallell to the assembly, it'll unlock itself and you can then completely disconnect the harness. It's easier than I'm describing it.
You will be able to drive the car. The ABS warning light will illuminate and the anti lock brakes won't engage if you make a panic stop, but the conventional brake system will remain totally unaltered.

This is your $0 solution. I guarantee it completely.
posted by Jon-o at 8:15 PM on July 29, 2010

it pulls down the whole data bus. Absolutely, Jon-o, thanks for that. I do have an ABS failure and had no idea that it could have an effect on the ECU. This is really great news and I will try it out today! Thanks for saving me a ton of $$, and thanks to every one else too!
posted by snsranch at 8:50 AM on July 30, 2010

And if your ABS controller has gone south you can have that rebuilt instead of getting a new one. Ask on the forums for someone in your area, after searching first.. Very common problem on Audi and WV.
posted by Ferrari328 at 12:36 PM on July 30, 2010