Festival of warning lights and beeping!

mowog

mowog

Member
Sorry for the mysterious title, but I don't know what is wrong, and it's easier to post someone else's YouTube clip than to try and describe the issue.


The dude in the video triggers the fault at about 3:40 into it. I get exactly the same error, warning lights, exclamation mark, beeping etc. For me it seems to be triggered at parking speeds, possibly when I have a bit of lock on.

I'm struggling to isolate which fault codes relate to this specifically as there are just so many being recorded all the time, but some recent ones include...
  • 01330 - comfort system central control system
  • P0170 - fuel trim bank 1
  • 17961 - altitude sensor signal / intake manifold pressure implausible ratio
  • 17912 - Air intake system leak detected
  • 01314 - Engine control module
A few of things strike me as particularly odd about this little electronic tantrum...
  • The ABS light comes on, but the only fault code recorded in the ABS section when I scan is the 01314 one.
  • If I turn off the car and pull out the key, then it usually resets and everything is fine again next time I restart.
  • On one occasion the same urgent warning was also paired with an inability to rev above tickover.
Thanks in advance :)
 
A faulty yaw sensor can often trigger the ABS warning lamps during slow speed maneuvering.

This would normally flag a fault code. Mine did using a genuine VCDS cable

Cheers Spike
 
OK, that's interesting. Any idea what subsystem the fault code might appear under? I did treat myself to a half-decent VAG compatible code reader, so I can see more than just OBD stuff. Also, where does this yaw sensor live, physically? I'm assuming it's attached to the bodyshell somewhere...?
 

ESP and ABS fault lights - Yaw rate sensor

Hi, on my bro's A2 he has a fault code as follows and ESP and ABS lights are lit on the dash. 01542 - Yaw rate sensor (G202) 57-00 electric circuit failure So my query is where is this sensor located on the A2? ( its the 1.4 petrol if it makes any difference). No google result on its...
www.a2oc.net

Cheers Spike
 
Just seen same thing in 1.4 petrol, it would do it all the time though not just after a drive and would be very anemic prior.

It had a EGR blanking plate that previous owner had installed on 1 of the 2 bolts, only blanking it about half way and it wouldn't go once it slipped off away enough.

No idea why it had ABS lights as well, after fixing the leak ABS light gone away as well, but that leak brought pretty much same symptoms, it would hunt around at idle like that but would not cut off unless I'd rev it and let it go down, it would just drop down to stop.

Feel around the throttle body and intake part for any air leaks, it would whistle and pull quite hard as seems vacuum is fairly strong in there.

---
Altitude sensor signal/intake manifold pressure implausible ratio
Air intake system leak detected
Load detection value below lower limit
---

had an ABS error as well but do not have note of what it was.

Had fuel trim and engine control module pop up and go away as well.
 
Last edited:
Thanks for that - really interesting. I actually spent last night and this morning before work taking the throttle body and EGR valve off to check them over and give a good clean, so I'll do as you say and check very carefully for leaks once it's all reassembled.

Decided that I may as well investigate the ABS sensors while the car was in the garage. Both were positively welded in. With a liberal soaking in WD40 I managed to lever one free once I had the brake disc and backing plate off. Not so lucky with the other though - I now have half a snapped ABS sensor stuck in the hole in the hub carrier.... ?
 
I cannot recall what error ABS was reporting but it was something to do with engine, I ignored it at the time as wanted to get engine running alright first, once I did that ABS fault cleared along with all other faults, it had a ton too that kept popping up due to that leak, seemed quite odd a leak in the intake setting off ABS :rolleyes:

I think it had something with comfort control module as well that went away after sorted that blanking plate too, at first i thought throttle body flap was stuck as it had a really strong woosh constantly, but it was staying closed as ECU was trying to make sense i am guessing, as all that air was wooshing into the intake unaccounted for.

apparently there is a hose going around back of the throttle body too, as i came across some posts that it can wear through rubbing against brake line, tucked it away and put some tape around it as it had a little indent i could feel, just as prevention, though not worn all the way through to have a leak.

I don't think there is anything there that is dangerous to feel around with engine running, as I did.

Guessing it feels a bit weak at lower rpm/idle and a bit better/normal once it is in the higher RPM range.
 
My 1.4 used to do this at higher engine speeds, it was fixed by adding an extra earth strap from the engine to the chassis, which is probably worth a try.
 
OK, so I now seem to be moving backwards :confused:

Since buying the car a month or so ago I have done the following:
  • Full service (oil, filter, air, cabin)
  • New plugs
  • New HT leads
  • New MAP sensor
  • New ABS sensors (front)
  • New CV boots
  • Removed and cleaned EGR valve and throttle body
  • Fixed possible hole in mystery vacuum hose coming off the throttle body
Having got everything back together I now have an exciting new fault - a persistent misfire on cylinder 2! Yay!

I did find Phillipe's excellent thread, and maybe I'll stump up for a knock sensor before I give up and break the thing for spares...

My question is, where is the knock sensor located on a 1.4 AUA petrol? I'm peering up at the back of the engine from underneath, and I can't see anything that looks likely. Anyone got a photo they could share? ?
 

A2 1.6 FSI - Where is the Knock Sensor?

Is there any photo or a good description of the Knock Sensor position on 1.6 FSI? Appreciate any help!
www.a2oc.net

Seems to be all the way behind the block, I'd guess it'd be more likely to be a coil, easier to swap #2 coil with one of others and see if misfile bounces over to other cylinder, same with spark plug potentially? If it were the knock sensor I'd expect it to be more random than one specific cylinder.

If new spark plug was not gapped correctly that could cause misfire also, though to be honest I am all that familiar with petrol.
 
My car has just a single coil pack. I did try swapping the leads and plugs around between cylinders 1 and 2, but the misfire stayed on 2. Could still be the coil pack or the injector, but that thread makes a strong case for trying the knock sensor first I reckon.
 
The knock sensor is accessed from the top by removing the inlet manifold. Even then it’s done by feel not sight


Sent from my iPhone using Tapatalk
 
I found it! Put the car back up on ramps, undertray off, and eventually spotted it. Needed a torch, and had to peer at exactly the right angle from just to the right of the exhaust.

With one arm squeezed past the exhaust heat shield and the other looping over the offside driveshaft it was possible to undo the bolt and remove the knock sensor.

The part number is 030 905 377 C

I've ordered a new one (£5.86 from fleabay) so we'll see if that helps. I'll be honest, I don't hold out much hope.

With the existing knock sensor back in place I went for a drive, and the fault I've been trying to fix (i.e. explosion of warning lights and beeping) occurred within the first 50 yards of the journey... :confused:

SO... going back to that earlier suggestion that it could be the Yaw Sensor, can anyone tell me which subsystem on the diagnostics a fault code for that might live? I've looked, and I can't see anything. But with only a month of MOT left it's becoming quite urgent that I figure out what is causing this.

Would be extremely grateful for any further advice on this.
 
Measuring blocks in the ABS module. Lateral accelerometer. Block 004?? Also steering angle sensor can cause issues especially if someone has had the steering wheel off.
 
Are current codes same as previously? It still makes sense to me for it to be air leaking past the throttle body somewhere, baffled me at first but once I found the leak orchestra of alarms made sense, other than ABS warning coming up due to engine intake leak.

even relatively large leak was different to spot as it is vacuum in the intake, rather than blowing out somewhere.
 
Un4tural said:
Are current codes same as previously? It still makes sense to me for it to be air leaking past the throttle body somewhere, baffled me at first but once I found the leak orchestra of alarms made sense, other than ABS warning coming up due to engine intake leak.

even relatively large leak was different to spot as it is vacuum in the intake, rather than blowing out somewhere.
Click to expand...
Hi I Sprayed the area with brake cleaner & listen for engine note to pick up
Worked for me !
Brakes rely on vacuum for the master cylinder to function no?
Links to abs.
Hope that helps
Keith
 
kp 115 said:
Hi I Sprayed the area with brake cleaner & listen for engine note to pick up
Worked for me !
Brakes rely on vacuum for the master cylinder to function no?
Links to abs.
Hope that helps
Keith
Click to expand...
Wish I had thought of it! Poor manifold must've been confused on why it felt like a Thai massage in my case!
 
Thanks for all the replies so far - much appreciated.

I decided to try and be a bit more scientific about tracking down the source of my mystery fault, by seeing if I could repeatedly reproduce it.

After a lot of shunting the car backwards and forwards I eventually hit on a reliable way to trip the same set of warning lights. The right 'technique' seemed to be to engage first or reverse, bring the revs up to perhaps 1500rpm or so, then engage the clutch, beginning to move the car, but without giving enough throttle to compensate. If the revs dropped far enough below where they would normally be at tickover then the EPC, traction control and ABS warning lights would all light up. Despite what I said before, I no longer believe steering angle is a factor, as I was able to repeatedly trigger this with the wheels dead ahead.

Once the fault was triggered, simply turning off the ignition, waiting a couple of seconds and then restarting got rid of the lights, and I could try again.

The new fault codes recorded when this happens are...

Under the Engine section on my scanner,
  • 17961 - altitude sensor signal / intake manifold pressure implausible ratio
  • 17912 - Air intake system leak detected
And under the ABS section of my scanner,
  • 01314 - Engine control module
Now for the fun part - after repeatedly triggering this fault, each time stopping the engine and waiting a few seconds to reset the lights, it eventually seemed to become permanent.

Bearing in mind what others have already said about leaks, I tried liberally spraying around the intake manifold with carb cleaner, but it didn't seem to have an effect.

Then I noticed a very odd rumbling sound coming from the driver's side wing. There's a vacuum hose that disappears in there, which I think I've read goes to the 'activated charcoal filter'.

Can anyone tell me what that is, why it's needed, and if it might be the source of the problem? There is a thing that is probably either a sensor or an electric valve halfway along the hose - anyone know what that does?

I couldn't help noticing that if I pinched the hose tightly I could make the rumbling stop.

Here is a photo of the hose in question...
IMG_20210627_183308.jpg


Am now wondering if this could somehow be the source of my some of the problems....
 
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