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Discussion Starter · #1 ·
Hey, I've read the other threads about this, but I think I'm going to need some help diagnosing and fixing.

I inherited my 2005 b5 Passat last year from my father in law with a flashing airbag light. Not having a scan tool I left the light on until it was serviced this year at a friendly garage. Having read up on the fault, I ordered a replacement eBay part (at 1/4 of the price it's worth trying first right?) along with a diagnostic cable to reset the code. I know that in the past 5 years of ownership in my family it hasn't been in an accident and nobody has tinkered with anything.

The fault code says "no or incorrect setting"

When I pulled up the carpet I was greeted with the dreaded soaking underlay. As this appeared to be primarily by the rear passenger door, I assumed it was a door seal, checked when it next rained, found a leak and patched it.

I checked inside the ccu box under the passenger seat and found the unit dry with some small puddles in the bottom of the case but no watermarks or dampness on the actual connectors. I figured the water had seeped through from the back, or rolled there when parked downhill.

Anyway, replacement sensor trips the same error code. When I disconnect it completely it says "open or short" so obviously there is some signal present to the ecu. So now I'm assuming this might be a problem with the other end of the wires. Can anybody advise where the crash sensor is connected to, and if they have an other insight into what's causing the fault?
 

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Anyway, replacement sensor trips the same error code.
To my limited knowledge, Bosch and Siemens Impact Sensors were the only ones used on all Passats (1997-2005). What company manufactured the (assumptive, bad) sensor that came off your car?

If the cheap (ebay) version doesn't match what was originally on the car, that may be part of your problem.

I also can't believe you actually changed an impact sensor...without disconnecting the battery. You're quite the lucky one.
 

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Discussion Starter · #4 ·
Ok, so to resurrect this thread...I still have this issue, but before I spend more money on random ebay or scrapyard parts I just wanted to clarify something:

I'm using VCDS-lite, which obviously can't measure blocks to check the compatibility of the sensor to the airbag control module, but that doesn't actually matter, right? Figuring out that the sensor is incompatible is as simple as resetting the code and then turning on the ignition and waiting for the airbag light?

I know that I'm capable of replacing the sensor myself (yes, I disconnected the battery beforehand), but I just wanted to check that there's nothing extra a mechanic with a full VCDS could do here, as I'd rather not waste my time when I don't have the full version.
 

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Discussion Starter · #7 ·
That’s what I thought (though presumably VW do code the sensor during manufacture, as they all have the same P/N between models).

Went for a more expensive second hand one from a Passat. We’ll see if it works at the weekend I guess...
 

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The sensors do have an embedded code, but that is fixed during manufacture and can't be changed.
The sensors may have the same basic part number, but there are different sensors identified by the PN extensions.
If you fit the wrong sensor it should generate a fault code noting a mis-match; this code can be read with VCDS-Lite.

I think your problem is more likely in the wiring.

http://wiki.ross-tech.com/wiki/index.php/01222
 

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Discussion Starter · #9 ·
Fixed it by getting a sensor directly from another Passat rather than eBay!

While I was down there though I noticed the carpet was soaked again ?.

Need to figure out the ingress issue once and for all.
 
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