A6 Allroad - intermittent warning lights

[Lotobear]

Occasionally but now with increasing regularity I'm getting the full range of warning lights - tyre pressure, abs, parking brake, traction control and air suspension. This often happens where reversing oddly enough and can then just disappear as fast as it came. Car drives as normal.

I'm instinctively drawn to a wheel speed sensor, any other thoughts?

[Lotobear]

Still no further forward but pretty sure it’s not the battery. I’d say 80% of the time it’s triggered by low speed manoeuvres especially when reversing in full lock. It can resolve itself as suddenly as it comes. One odd effect is the sense that the engine is wanting to go when in drive with foot on the brakes waiting in traffic-seems to labour against the brake. Any thoughts welcome

[PushedDover]

I think I can offer my own experience in this - https://www.pistonheads.com/gassing/topic.asp?h=0&...

Faulty ABS Sensor / cables, can really FUBAR the brain.

[OldGermanHeaps]

What does a vcds scan say?

[Huzzah]

I had similar on a merc, full lock in reverse, bumps and bad weather seemed to be the trigger.

Traced it to the wiring for front wheel speed sensor.

[miniman]

Yes that set of faults was wheel speed sensor for me, that needed replacing and the loom re-pinning as initially the new sensor didn’t cure it. The car needs to know the wheel speed for all those systems to work.

As an aside, mine does seem prone to a lot of failed bulbs, parking sensors and general electrical gremlins like the infotainment rebooting randomly from time to time. I think I’m going to wind it in against something else.

[Dr G]

Just had an RS6 do this with very similar symptoms (was wheel speed sensor), albeit initially fooled by a worn-out main battery.

[Lotobear]

Thanks for comments - a scan showed a few fault codes but also front NS wheel speed sensor so I will do that first and see how it responds.

....I also have that shonky control box under the mid rear seat that occasionally throws a steering fault when the car is loaded with rear seats down so I will look into that as well.

[catso]

Lotobear said:

Still no further forward but pretty sure it s not the battery.

I had an A3, 3.2 DSG that had a bit of an appetite for batteries - got through 3 in the 12 years I had it.

If starting with a low charge in the battery, it would cycle all the warning lights.

Sometimes they would eventually go out and normal service be resumed but, on 3 occasions faults remained and the gearbox gradually stopped shifting into various gears until I was left stranded in neutral with no drive.

If I switched off and restarted it would generally be fine and a fully charged or new battery always solved the problem.

[Lotobear]

catso said:

Lotobear said:

Still no further forward but pretty sure it s not the battery.

I had an A3, 3.2 DSG that had a bit of an appetite for batteries - got through 3 in the 12 years I had it.

If starting with a low charge in the battery, it would cycle all the warning lights.

Sometimes they would eventually go out and normal service be resumed but, on 3 occasions faults remained and the gearbox gradually stopped shifting into various gears until I was left stranded in neutral with no drive.

If I switched off and restarted it would generally be fine and a fully charged or new battery always solved the problem.

I had the battery tested and it came out 'good' but I will not entirely discount it as another thing I've noticed is the effect appears to be more frequent in very cold weather.

...but with a new battery costing £230 I'm inclined to try other things first.

[Huzzah]

Lotobear said:

Thanks for comments - a scan showed a few fault codes but also front NS wheel speed sensor so I will do that first and see how it responds.

....I also have that shonky control box under the mid rear seat that occasionally throws a steering fault when the car is loaded with rear seats down so I will look into that as well.

Before replacing I'd try the following.

Jack it up, wheel off, ignition on. Full lock both sides and wiggle the wiring see if you can get it to trigger a fault.

[Lotobear]

Huzzah said:

Lotobear said:

Thanks for comments - a scan showed a few fault codes but also front NS wheel speed sensor so I will do that first and see how it responds.

....I also have that shonky control box under the mid rear seat that occasionally throws a steering fault when the car is loaded with rear seats down so I will look into that as well.

Before replacing I'd try the following.

Jack it up, wheel off, ignition on. Full lock both sides and wiggle the wiring see if you can get it to trigger a fault.

Thanks, that's a good suggestion!

[Lotobear]

So I decided just to let this develop, what I have noted:

1) It almost always occurs during low speed manouvering with maximum or near maximum steering lock on, mainly in reverse. Never when moving at speed
2) Putting into P, turning it off and immediately re starting the engine will always clear it
3) Far more prevalent in cold weather - It has not happened at all today even in the usual trigger conditions - the air temp is now 10 degrees

I've looked at the battery condition with a Carly reader and it showed 14.5v at idle.

I am leaning towards the battery as full lock in cold conditions would I imagine place a high demand on the steering motor.

I've tried to look at the battery but since you have to remove the air tank to remove the holding down clamp, I abandoned it. But the battery does appear to be a replacement (has Jap writing on a bit I can see) and not the original VAG fitment. Car is 2013 and on 78,000 miles.

Any other suggestions in the light of this?

Cheers

PS: Carly throws up around 13 codes, all related to the systems which are affected (wheel speed, parking brake, air suspension, tyre pressures, traction control) but the trouble is it does not point to which one caused it.

Edited by Lotobear on Friday 20th February 13:02

[PushedDover]

Lotobear said:

So I decided just to let this develop, what I have noted:


PS: Carly throws up around 13 codes, all related to the systems which are affected (wheel speed, parking brake, air suspension, tyre pressures, traction control) but the trouble is it does not point to which one caused it.

Did you not see my post:

PushedDover said:

I think I can offer my own experience in this - https://www.pistonheads.com/gassing/topic.asp?h=0&...

Faulty ABS Sensor / cables, can really FUBAR the brain.

original post linked ^^^^

PushedDover said:

After moons of finally getting the 360 cameras arranged and fixed by the Audi Dealer, I have only had it back a week or so.
I drove to Manchester Airport Monday, got back in it last night to drive home to find a christmas tree of error messages:

<ding> Main Beam assist : System Fault !
<ding> Stabilisation control (ESC /ABS) : Fault!
<ding> Start / Stop : System Fault !
<ding> Air Suspension : System Fault
<ding> Brake Servo Restricted
<ding> Audi Adaptive light : System fault
<ding> Parking Brake ! {not on}
<ding> TPMS Tyre Pressure System Fault

<ding>

https://www.dropbox.com/s/ltjq01uscy6q658/23e5c3a1...


In addition all parking sensors are borked, the cameras, and cruise control

Deep Joy.
Tried turning it off and back on again etc. Gave it a look round and hoofed it home while copilot googled.

This morning I finally found the battery and tried to power it all down to reboot, and surprised to see the terminals totally dry connections.

• bump / resolution *

I noticed in addition to the above errors for example, the Cruise control was unavailable, the parking sensors unavailable and the remote release of the boot was unreliable. The Sat Nav was also erroneous and slow.

Lord only knows why - but the causation of all that palaver above was a faulty ABS Sensor. Why an ABS sensor would cause everything else to stop, or through a hissy fit, is surely bad design?!

Edited by PushedDover on Friday 20th February 13:13

[miniman]

Lotobear said:

So I decided just to let this develop, what I have noted:

1) It almost always occurs during low speed manouvering with maximum or near maximum steering lock on, mainly in reverse. Never when moving at speed
2) Putting into P, turning it off and immediately re starting the engine will always clear it
3) Far more prevalent in cold weather - It has not happened at all today even in the usual trigger conditions - the air temp is now 10 degrees

I've looked at the battery condition with a Carly reader and it showed 14.5v at idle.

I am leaning towards the battery as full lock in cold conditions would I imagine place a high demand on the steering motor.

I've tried to look at the battery but since you have to remove the air tank to remove the holding down clamp, I abandoned it. But the battery does appear to be a replacement (has Jap writing on a bit I can see) and not the original VAG fitment. Car is 2013 and on 78,000 miles.

Any other suggestions in the light of this?

Cheers

PS: Carly throws up around 13 codes, all related to the systems which are affected (wheel speed, parking brake, air suspension, tyre pressures, traction control) but the trouble is it does not point to which one caused it.

So two thoughts on this:

1. If it's happening at low speed on full lock, I'd suggest you are putting some strain on the wiring to the NS front wheel sensor that was showing the fault code and it correlates with my need to have the connector re-pinned on mine.

2. Replacing the battery is not too difficult, you do need to move the suspension valve block but it's not complicated and doesn't require disconnecting any of the air lines.

[Dr G]

Look at live data from the wheel speed sensor both driving and stationary. Have all 4 on screen and a passenger monitor for differences. The one I made reference to would sporadically show 2mph when stationary.

[Lotobear]

Thanks for the comments chaps, and the live data suggestion is a good one - will try that.

A wheel speed sensor is the obvious start point but what I can't understand is why air temperature would affect that? With the present mild double digit temperatures the issue seems to have all but disappeared if not completely stopped.

I will do a visual inspection on the sensor wires and try some switch cleaner on the connector pins, in addition to looking at the live data

[miniman]

To be honest, you’ve had this issue for 4 months. At some point you have to change the wheel sensor!

[catso]

Recently replaced a wheel speed/ABS sensor on my Son's Golf but the only errors that was throwing up was ABS/wheel speed faults on that wheel.

A slightly awkward job though because, despite being plastic it had corroded into the housing and so the head broke off whilst trying to remove it. I had to screw a self-tapping screw into the body and 'tease' it out but, problem solved and the part wasn't expensive.