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Discussion Starter #1
Hello everybody,

I ran into a trouble code P1479 - 008 - Brake Boost Vacuum System - Mechanical Failure. Most usual causes have been eliminated and it 99% percent sure that this is NOT a vacuum leak.

The relay of that pump has been replaced. Because it burned. However, after the replacement this error persisted, but not every time the car starts.

I took it to a dealership and they told me the vacuum pump does not provide sufficient pressure.

This leads me to believe that the pump is the culprit - most likely prior to stage of complete seizure - drawing sufficient current to burn a relay, but not sufficient to burn a fuse, most likely due to a rotor problem.

So, the question is - can this pump be (reliably) repaired or do I need to go with a new one?

Subsequent question - OEM or aftermarket part - since the price is considerably different?

Of course, all suggestions are welcome and appreciated.

Thanks.
 

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Is there anything a scan might show up .... I dont know .... just a first thought...

Strange also as i have not seen brake booster probs in the couple of years i have been here
 

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Discussion Starter #3
Is there anything a scan might show up .... I dont know .... just a first thought...

Strange also as i have not seen brake booster probs in the couple of years i have been here
Scan showed the error I mentioned:

17887 - Brake Boost Vacuum System
P1479 - 008 - Mechanical Failure

... and nothing else. For the last 1500 kms.

Probably because there aren't as many gasoline driven Touaregs around. Diesel is the usual, overwhelming preference.
 

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Why don't you get a used one for 60 or 70$ to troubleshoot and rule out the pump if it is the issue.
Here is one on ebay


Part number for LHD is 8E0927317H. Last version.

It all started with 8E0927317 and then was upgraded to A to B.... to H for the Touareg.
You can test with an 8E0927317 or and 8E0927317B

Here is a link to a Touareg 2007 B version:


Total amount of the test is less than a diagnosis session at the dealer.
If you have VCDS you clear the codes and test.
If it work you either keep it or get a new OEM one. price is around 370$.
For me it's either OEM used or OEM new for this kind of parts.
 

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Here is a pdf of the vacuum pump setup. I myself will be looking into the vacuum pump to booster hoses as I started having a soft pedal and I need to check for leaks. There is a sensor on one of the hoses (hose 2). It might be that this sensor is not working and putting strain on the pump. Just a wild guess. I will check this sensor myself when I get the time. It is hidden behind the engine where the vaccum hose goes into the booster. And there are a bunch of check valves too. The sensor is probaly not present on your Touareg. I will have to confirm or you can call vw to check.
Sensor part number: 036906051G. Price around 60€

Is your braking ok?
237373
 

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Discussion Starter #8
Thanks TRespect. This is really an overwhelming quantity of really useful info.

Braking is fine - no doubt there whatsoever.

The guy at the shop mentioned the possibility of valves being the culprit too. Not the sensors, though, but the guy at the shop mentioned that it's impossible to measure pressure at every point in the system, so some guesswork is mandatory.

I'll have a look at these materials and get back to you once more.

Meanwhile - thanks. A bunch of millions. You did really great work.
 

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You're welcome. ETKA confirms that the pressure sensor is present on Tregs with automatic transmissions only.
And I've read the check valves might go wrong like you said. I will be deleting all the VW hard plastic hoses and rewiring this part with some good silicone hoses and new check valves when I get the time. Check valves are cheap. VW do not sell them separately for this setup. They sell the whole hoses and those guys go from a100$ to 200$ a hose.
You can lookup the checkvalve part number on the valve itself or use something like this 058905291K. I will be getting some metal check valves from aliexpress and testing to see if they are ok for the job. Something like this:

I don't trust other than OEM parts with critical systems like the brakes but I will tear open some of the valves and test them before deciding. I like the metal heavy duty part.
 

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Discussion Starter #10
Hello again,

I received the new vacuum pump. Tried it at the workshop and returned it immediately. It's not the source of my problem since the old pump is working just as good as the old one.

The problem, as the mechanic said, is one of the following:
  • vacuum sensor
  • set of vacuum hoses as you mentioned.
  • brake servo drum (responsible for brake system pressure - not sure about the proper translation?)
I'm assuming it's the vacuum hoses (probably due to their age), so I ordered them. They're heftily priced bits (400 EUR), but I'm hoping to solve the problem and finally make the engine ready for LPG installation.

Not sure about the brake servo drum - the manual is not mentioning it as a possible cause of P1479 error. To add, the brake pedal has never been hard and no braking problems whatsoever. If it did, I would expect the dash to light up like a christmas tree and other errors to be present on the VCDS.

And final question - is there a measuring block for the vacuum sensor? Is there a "requested" and "actual" value to it - as there is for turbo pressure - for instance? Is it possible to deduce from measured values that the sensor might be faulty?

It's a great idea you have for hoses replacement. I just wish I had the time and how-to like you do.

Thanks again.
 
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