Whole bunch of fault codes...where to start?

G

gmarsh500

New Member
Thanks in advance for reading!

I have a 2004 1.4TDI with 180k miles on the clock. I am very fond of the car (of course) and would really like to keep it on the road as long as possible.

The car drives very well and has been serviced regularly.

However, I have an ABS and Airbag warning light on, so I recently got a diagnostic scan. It has produced a number of error codes, unfortunately.

Does anyone here have any experience of these particular codes? If so, how expensive were the repairs and which are the ones to really worry about?

I don't mind spending a bit of money to repair them, but I fear that some of these might be serious enough to make it uneconomical

Here are the results:

ABS
029C - Voltage supply control units faulty
0122 - Rear lft wheel speed sensor incorrect/no signal + mechanical fault

Airbag
024C - Driver's front airbag igniter circuit high resistance

Engine
42A0 - Glowplug circuit defective cyl 2
42A1 - Glowplug circuit defective cyl 3

Instruments
040F - Cooland temp sensor open circuit
0303 - fuel level sensor open circuit

Central Electronic Module
055A - Interior monitor alarm trigger faulty
055B - Driver's door alam trigger faulty
0619 - Left read door lock/unlock faulty
 
Due to the South West meet a few people who might respond normally may be unavailable today so I'll pitch in quickly with some ideas.

The codes are a bit of a mishmash, which leads me to the following thought processes :

First question - how recent is the battery? If it is getting on a bit and there have been voltage drops (particularly while starting in winter), this can cause all manner of spurious error codes to be lodged in the memory of various ECUs, so some of the above may be red herrings that can be cleared and won't come back (unless there is another voltage drop). Even now (at 16 years old + minimum) there are reports on here of people going to swap the battery and finding it is an original Varta complete with an A2 8Z0 part number printed on the top surface - I have had two on my cars that were clearly beginning to die (but had definitely got their money's worth at 14 and 15 years old).

If the coolant sensor has an open circuit, does your car visibly reach temperature normally on the dial when run? If not, replacement temp sensors are around a tenner and maybe 20-30 minutes to swap over if it goes smoothly. Secondly, does the fuel gauge work consistently? If it does, then again this may be a red herring. I had the coolant sensor fault (commented as 'intermittent') on one car, and this manifested itself as the temp gauge working sometimes, then suddenly going to 0 after going over a pothole, and then randomly coming back. New sensor resolved this problem.

Glowplugs could be a genuine issue given the age and mileage. Providing they aren't seized, my understanding is that these are a bit like sparkplugs to replace - unscrew & refit. However, you need to be certain that you are fitting the right ones (there are different ones for 75hp and 90hp models that run on different voltages)., and a diesel doesn't necessarily need the glowplugs to run, certainly in summer time.
 
Robin_Cox said:
Due to the South West meet a few people who might respond normally may be unavailable today so I'll pitch in quickly with some ideas.

The codes are a bit of a mishmash, which leads me to the following thought processes :

First question - how recent is the battery? If it is getting on a bit and there have been voltage drops (particularly while starting in winter), this can cause all manner of spurious error codes to be lodged in the memory of various ECUs, so some of the above may be red herrings that can be cleared and won't come back (unless there is another voltage drop). Even now (at 16 years old + minimum) there are reports on here of people going to swap the battery and finding it is an original Varta complete with an A2 8Z0 part number printed on the top surface - I have had two on my cars that were clearly beginning to die (but had definitely got their money's worth at 14 and 15 years old).

If the coolant sensor has an open circuit, does your car visibly reach temperature normally on the dial when run? If not, replacement temp sensors are around a tenner and maybe 20-30 minutes to swap over if it goes smoothly. Secondly, does the fuel gauge work consistently? If it does, then again this may be a red herring. I had the coolant sensor fault (commented as 'intermittent') on one car, and this manifested itself as the temp gauge working sometimes, then suddenly going to 0 after going over a pothole, and then randomly coming back. New sensor resolved this problem.

Glowplugs could be a genuine issue given the age and mileage. Providing they aren't seized, my understanding is that these are a bit like sparkplugs to replace - unscrew & refit. However, you need to be certain that you are fitting the right ones (there are different ones for 75hp and 90hp models that run on different voltages)., and a diesel doesn't necessarily need the glowplugs to run, certainly in summer time.
Click to expand...
Thanks a lot for the detailed reply!

The battery is not the original, but I have not changed it since I have owned it and I don't know its condition. There are no electrical issues (apart from the passenger window sticking a little sometimes) but the previous owner did attach an after-market soundsystem (now removed), which may have interfered with something and the leads are still attached:

image0.jpeg
image0 (1).jpeg


I didn't consider this an issue initially...do you think it could be?
 
Who scanned the car for you? Did they clear the stored codes either before or after recording them? The airbag warning light for one absolutely won't go away until the stored code has been cleared

There's nothing on the list of fault codes you've provided that is likely to be particularly expensive to fix.

Like Robin, I wonder about the state of the battery as a trigger for some of those fault codes.

I'd certainly be looking to remove the wiring that previously connected to the after-market sound system.
 
What diagnostic scan kit was used, VCDS or other?
First thing is to use vcds to clear the errors, as some are, probably historical.
Battery condition is important, as low volts will give false errors.
With engine off, ignition off, the battery should read 12.5 min, 13.2 ideally. With ignition on, but no engine running, but head lights on, battery should still read 12.5.
Much less than that, and battery charge/replacement is next move.
Mac
 
Thanks for the replies.

The scan was done at a local garage, and I am not actually sure what scan kit was used or whether they attempted to clear any on this occasion. I just asked them to do the scan while it was in for some tyres to be changed, so I don't think they made any attempt to fix the problems.

Is it worth getting my own scanner in this situation?

In general, do you think it is likely to be cheaper to let a garage take it from here or is it reasonable to invest money in a scanner, battery, etc and try to do things myself?
 
Get your own scan kit. Cheapest is VCDS-LITE, free download, eBay cable, under £10, any Windows laptop, XP to 10.
At the very least, you'll have an insight into what is wrong, and what you want your mechanic to do. Plenty of knowledge on here. Find a mechanic with VAG expertise, and share your scans with him.
Check out the Free Scan Register on here as a starter, to see how it goes, and chat about your results.
Clear codes, drive, rescan.
Good luck.
Mac.
 
Get THREE things. One VCDS and cable. Two a test meter. Three a spare key for your car. Have all three before even thinking about any upgrades or modifications.
 
PlasticMac said:
Get your own scan kit. Cheapest is VCDS-LITE, free download, eBay cable, under £10, any Windows laptop, XP to 10.
At the very least, you'll have an insight into what is wrong, and what you want your mechanic to do. Plenty of knowledge on here. Find a mechanic with VAG expertise, and share your scans with him.
Check out the Free Scan Register on here as a starter, to see how it goes, and chat about your results.
Clear codes, drive, rescan.
Good luck.
Mac.
Click to expand...
Thanks for the advice. I will try VCDS-LITE as "plan A", in that case.
 
gmarsh500 said:
Thanks for the replies.

The scan was done at a local garage, and I am not actually sure what scan kit was used or whether they attempted to clear any on this occasion. I just asked them to do the scan while it was in for some tyres to be changed, so I don't think they made any attempt to fix the problems.

Is it worth getting my own scanner in this situation?

In general, do you think it is likely to be cheaper to let a garage take it from here or is it reasonable to invest money in a scanner, battery, etc and try to do things myself?
Click to expand...
Hi gmarsh500,
I work in Cambridge so could scan & then clear you codes for you with a fully functioning VCDS system allowing you to drive around for a period & then rescan as a lot of these faults can be historic, to determine what if any are left .
Hope that helps
 
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kp 115 said:
Hi gmarsh500,
I work in Cambridge so could scan & then clear you codes for you with a fully functioning VCDS system allowing you to drive around for a period & then rescan as a lot of these faults can be historic, to determine what if any are left .
Hope that helps
Click to expand...
That's very generous of you. I'll send you a message. Thanks!
 
UPDATE

Thanks again for the advice. It has probably saved me a bit of money already.

I managed to get VCDS-lite working and cleared most of the faults, including the airbag warning light.

However, the ABS warning light returns after driving a short time, and this is the fault code:

0122 - Rear lft wheel speed sensor incorrect/no signal + mechanical fault

(See post below)

Would now be the time to go to the garage?

Thanks again everyone.
 
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Or just replace the sensor yourself. Wiring needs to be checked. Chance there could be a loose plug on the sensor. At least there is now less for the garage to over charge you for.
 
Out of curiosity exactly what wheel and size tyre is on the left rear and does it match the other 3 tyres for size?
Can you also double check the error code you have?
 
audifan said:
Out of curiosity exactly what wheel and size tyre is on the left rear and does it match the other 3 tyres for size?
Can you also double check the error code you have?
Click to expand...
I have checked and actually I got the code wrong in my earlier post. I will post the screenshot of VCDS below.

I recently had new tyres put on all around, and they are the same size. (I did wake up to find the front left tyre flat this morning. I have reinflated it and driven it a little, but I guess it has a slow puncture. Not sure how good a job this garage did, to be honest.)

Here is the error:

ABS.JPG
 
audifan said:
Did you have an ABS problem BEFORE the new tyres were fitted?

This explains the error code more...

00290 - Ross-Tech Wiki

wiki.ross-tech.com wiki.ross-tech.com
Click to expand...
Yes, the same warning was present before the new tyres were fitted.

I also have a brake-pad-wear warning light on, even though the brake pads have been changed recently. Could it be related?

I will try to check the speed sensor on the wheel, but I am not really experienced enough to know what I am looking for! At least I can take it to the garage with more details.

Thanks for your help.
 
Tyre going flat is most likely to be corrosion of the rim - the SE 6-spoke rims in particular are prone to this happening - I have 2 or 3 in the collection (20 SE rims!) that leak slowly. The tyre place needs to give them a really good clean up where the tyre bead engages with the rim ; the other place that causes issues is the valve seat. I worked this out on mine when washing the car (the first time) the valve was at the bottom of the wheel and where the water pooled in the valve tunnel there was a small stream of bubbles like sparkling water, and then when the wheel was off water poured onto it revealed another area that fizzed gently.
 
gmarsh500 said:
Would now be the time to go to the garage?
Click to expand...
Probably, although I realise that the conversation is still moving forward on this.

I'd encourage you to give some thought to where you take the car to get such problems sorted (and your annual service). In general, it's best to look for an independent Audi / VW specialist who is able to carry out their own MOTs, and stick with them providing you're happy with their work and prices.

I don't know either business, but VW Technics in Willingham http://www.vwspecialistcambridge.co.uk/ and audi-specialists.co.uk in Burwell https://www.audi-specialists.co.uk/ have both been going for some while and are likely to be familiar with the A2.

I have my A2 serviced each year by a local specialist just ahead of the MOT - they give the car a full check over and I've never had any issues come the MOT.
 
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