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**sabbySC** · 09-12-2011, 09:58 PM

Re: Mk4 fault codes

Off the top of my head, I would say your need a voltage regulator or alternator.

Also a new CTS sensor.

**stefan** · 09-12-2011, 10:03 PM

Re: Mk4 fault codes

I seem to recall on the TDI, relay 109 could cause goofy errors if the contacts became corroded, as it is one of the main power supply relays. Don't know a heck of a lot about it, but maybe something similar on 1.8?

**shconer** · 09-12-2011, 10:45 PM

Re: Mk4 fault codes

A lot of those codes could come from a dying battery. Some modules can be more sensitive than others to low voltage spikes. So if your battery is on its way out when you start the car the low voltage from cranking could cause the many modules like the door and ABS that communicate via CAN to lose contact with the PCM which has a higher capacitance to deal with situations like that and still start the car. Once the car is started the voltage quickly rebounds and the modules communicate again and the codes get stored as history. If the battery is good and you clear the codes and they don't come back I would say it was just the crappy old battery. You could argue that if the battery was removed then the codes would be erased but if the battery was professionally changed its not uncommon to use a memory saver to keep the trip, radio presets and stored codes. Thats my guess.

**MechEngg** · 09-12-2011, 11:09 PM

Re: Mk4 fault codes

Hmmmm could it be due to the fact that the owner (not me) installed a winter start battery?

Also I cleared the codes and took it for a short drive before I scanned it the second time

**The_Jerbel** · 09-13-2011, 12:00 AM

Re: Mk4 fault codes

Any unusual beeping or flashing ABS/brake lights?

**MechEngg** · 09-13-2011, 06:01 AM

Re: Mk4 fault codes

Nope the only instrument panel light is the airbag light. And it has a Neuspeed chip but i don't think that its covering up any lights

**Wildfire** · 09-13-2011, 03:31 PM

Re: Mk4 fault codes

This may sound like a silly question. Have you adjusted your drivers side seat/ moved it anyway recently?

**shconer** · 09-13-2011, 06:53 PM

Re: Mk4 fault codes

How about the battery cables and connections. Cooler weather can loosen the connections.

**MechEngg** · 09-13-2011, 07:09 PM

Re: Mk4 fault codes

Thanks for all your guys' help, not going to bite into this car though. Just got inspected by VW with $8000 in repairs :S

**Geobmx4life** · 09-13-2011, 07:46 PM

Re: Mk4 fault codes

Originally posted by MechEngg View Post

Thanks for all your guys' help, not going to bite into this car though. Just got inspected by VW with $8000 in repairs :S

WOW...just out of curiousity...did you think about taking it to George? I don't trust the VW dealers myself!

**MechEngg** · 09-13-2011, 07:49 PM

Re: Mk4 fault codes

I tried, he is booked until the 27th. But no big deal, wouldn't want to try to deal with all these problems that came up anyways

**sabbySC** · 09-13-2011, 08:56 PM

Re: Mk4 fault codes

What does $8g in repairs entail??

**CGDoig** · 09-13-2011, 10:01 PM

Re: Mk4 fault codes

^same question, I'm curious as to what your idea was too.

**Wildfire** · 09-14-2011, 06:12 AM

Re: Mk4 fault codes

I had the same airbag light and codes come up twice when I had my Mk4 1.8T.
It happened during one winter when the weather was really cold. I had it cleared.
Exactly a year later the airbag light came on again, same codes. Its defo not the battery as I had installed a brand new one. I pulled out my cars paperwork and the first owner (I was the second) had the drivers seat and some cables replaced under warranty as the airbag light kept coming on.
Now I drove a two door GTI, I never moved my drivers seat to let passengers in the back. They would get in the passengers side. Oddly enough I do remember moving my seat to let my little niece out, thats when the airbag light came on the next day.

I searched around the internet and a few people had a similar problem with air bag lights and cables with the MK4. I read one guy got so fed up he replaced the connectors himself.
I never found what exactly the problem was but after searching around google I came to the following conclusion:
1. At very cold temperatures, the cables/wiring harden to an extent that when the seat is moved, they don't flex as much.
2. VW airbag seat wiring+connectors are very very poor.

But having said that, you drive a Jetta so the above makes no sense why it would happen to you.

$8,000 worth of repairs? wtf?!

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Mk4 fault codes

Mk4 fault codes

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