A4 problem - ABS/ESP warning lights

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Rosco191

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Having a strange problem with my Avant, and I’m hoping you guys can offer some advice!


It’s a 2004 A4 TDCi Sport Avant, (non Quattro) and I recently bought a genuine set of RS6 18” alloys for her.


Put the rears on, and went to put fronts on to find they were nearly flat. Drove to garage to pump them up, and the ABS warning came on along with ESP saying there was a fault in the system. This has never happened before, and only after I put the 18” alloys on the rear and had the standard 17” alloys on the front. Will this short drive with different size wheel on each axle confuse the system?


The only other thing I can think of, is I had to use a bit of force to get old wheels off as they were tight on and wonder if I’ve damaged something?


Any ideas?

Cheers
 
If it was the wheels, i'd expect the light to go back off when you put the 18's on the front.

It also would only happen if your new wheels have the wrong size tyres on them. If they were fitted with the correct size tyres, the car wouldnt be able to tell any difference between the 17's and 18's.

If its stayed on, you need diagnostics to find out why its on.
 
Agreed as above, if the rolling circumference is the same, it shouldn't error, however did you disconnect or catch the abs connector by any chance?

It could just be its thrown an error & given the system, it needs clearing to reset the system fully.
 
I bet you got a loose wire on your break pad sensor .. Easy fix just pull the connector out and put a bit of wire there to make to Ecu think every thing ok but remember to check every month of wear on pads
 
the brake pad sensor wire wont show a ABS warning

only a low pad warning
 
Thanks guys, will have a better look at weekend in the daylight.

Any idea what size tyres should be on the RS6 wheels? The guy said they came off an A4 so I had assumed they were right size...appears not.
 
tires are probally the right size but running 17's on front and if genuine rs6 alloys there will be 18/19's so you will have a difference in the rolling height of wheels and this will be sending abs system nuts press and hold the button for traction and turn it off car will drive normally then
 
Hi All, I have recently bought a A4 Cabriolet 2.5TDI V6 (100,000 mileage, 2004, 2 cambelt changes) and within a day the car fails to start intermittently with the flashing PRNDS! The dash illuminates the ESP and ABS lights and the engine will crank over but the car fails to start. I have to either keep taking the key in and out until the flashing PRNDS goes back to normal (which can take between 1-30mins) or I have to wait about 10-15mins after which the car will usually start. It is definitely a sensor issue as when the car starts, it drives perfectly and there are no mechanical issues or noises. The worst thing is the car cuts out suddenly whilst driving and this locks the steering and ESP and ABS lights come on and the flashing PRNDS comes up on the dash after which I could be stuck for upto 20-30mins!

I have taken it to an Audi technician who found a major fault which was the Crank Position sensor (g28 sensor) which I replaced immediately and also carried out full service as this was due. Problem still persists and technician is baffled as to what it can be! He is sure the gearbox transmission is fine and doesn't think it is the fuel pump but not certain. He has a hunch that it could be the throttle valve but there is no loss in performance, no juddering in D, no loss of reverse, idles perfectly, no excessive smoke. I'm at a loss as to what it can be and do not feel safe driving the car. Nor do I want to throw money at the car without knowing for sure what it can be. The brake light on the gearbox doesn't illuminate when this happens and the brake lights remain on constantly whilst the flashing PRNDS lights are flashing.

The car has full service history but should have had a gearbox oil change 20,000 miles ago. Mechanic does not believe this to be the fault.

Any help would be appreciated.
 
Get a diagnostic done with VCDS/Vagcom.
You should have fault codes logged if the PRNDS & ESP/ABS warning lights have been on.

It's important to change the ATF & filter on the autos at the correct intervals as old ATF will cause problems. Also there are known issues with the Audi multitronic auto, & if that's what you car has fitted prepare to spend £££££££££'s.

Another thing worth checking.
There are 2 water drain plugs in the Plenum chamber which get blocked up so check for water ingress underneath the Battery & Servo. The ECU is also located in that area & the seal is also known to fail & cause all sorts of electrical chaos if water gets in there.
 
Last edited:
VCDS showed 3 intermittent faults:

Hydraulic Fuel pump
Throttle valve
Water Temp sensor

These were cleared by the technician but reappeared, he is not sure what the issue is and stated the gearbox ECU is fine and has trouble connecting with the engine ECU when the problem occurs because the engine ECU shuts down. It doesn't allow his VCDS to connect to the engine ECU either when this happens and said that these old engines are outdated and if it was a newer engine it would have connected.

There was no codes linked to ESP/ABS or transmission, which is what confused the technician.

Do you think this issue can be fixed if I change the gearbox oil or is it too late for that? I wasn't aware of the intervals until I purchased the car and had this problem :(
 
Sounds like an electrical issue rather than old ATF to me. Never had a problem connecting VCDS to an A4 B6 myself.
As I said earlier start looking for damp electrics. Check for damp carpets in the driver, & passenger footwells too.
 
Have noticed that the rear passenger and front passenger foot wells are slightly damp...if it is an issue regarding the water ingress in the plenum chamber is this an easy fix? A mechanic said it was worth cleaning the MAF sensor and throttle valve with carb cleaner but not sure what this will do as there is no loss in performance.
 
AudiLeon said:
For the original problem. Check your brake lights.
Click to expand...

Brake lights remain on constantly when the problem occurs along with ESP/ABS lights on dash and flashing PRNDS.

Have got out of car to check and brake lights are constantly on. No brake pedal light on gearbox either.

When the car does decide to start, the first sign I notice is the brake pedal switch on the gearbox illuminates as it should and the flashing PRNDS disappears to leave the normal highlighted P at which point I know the car will start.
 
Sorry should have mentioned this earlier but car is most prone to cutting out/ not starting when the engine is warm and never fails to start first thing in the morning or after an hour or so of leaving the car parked.
 
Failed brake light switch can cause a quite a few problems. It's worth replacing & a cheap (£10) easy fix.
You also have a failing coolant temp sensor too which is probably the cause of your hot starting problem. Use a genuine CTS (£25ish) as cheap aftermarket parts are notorious for failing.
 
Cheers pal, I would imagine such cheap and easy to replace parts would not cause a car to be so unpredictable and cut out whilst driving as and when it pleases. I will replace these and let you know how I get on...appreciate the help Paul :)
 
I think water ingress is more likely a cause of the cutting out. There's a bunch of relays under the ECU that can get water logged if the plenum chamber drains are blocked or the ECU box seal is leaking.
 
I assume these relays will have to be replaced? And any ideas where i can get a new ecu box seal?
 
Well that depends if they have had water contamination or not. Usual sign of this is damp carpet in the driver footwell up around where the brake, clutch & accelerator are located. Main dealer or TPS for a new ECU box seal.
 
I took the battery out and found the plenum chamber but can find only one drainhole which isnt wet or blocked...cant see the ecu or relays anywhere there do you know exactly where this is? Everything looks dry and there is no dampness in the drivers footwell just the passenger and both rear passenger footwells are slightly damp.

Im very confused
 
Other drain is under the brake servo. ECU box is on the bulkhead to the left of the servo.
 
If all seems fine and dry is it worth looking under the brake servo? Do you know any other reasons engine can cut out?
 
I think you should PM adamss24 as he's a bit of a 2.5 tdi guru, & far more knowledgeable than myself. Surprised he hasn't chipped in yet, but he's the man to talk to.
 
Dont have the time or tools to get to the final screw under the wiper motor at the moment and it is a multi tronic gearbox...will message adamss24
Mechanic who looked at the car now doesnt think its water but defo thinks its an electrical issue with the car.
 
The symptons for failed ECU dont match the issues on my car as there is no loss of reverse or jerking/juddering when taking off. It just shows esp and abs lights on dash when problem occurs along with flashing prnds ut i can still change gears and car recognises this as parking sensors activate even though car is switched off
 
I agree it sounds like an electrical fault which is why I suggested looking for signs of water ingress.
Posting the actual fault codes could be helpful too.
 
Just waiting on the Tech to email me the codes he had stored from the car...will be posting shortly.
 
Just to let you know, I had an OBD2 plugged in and had the brake light switch changed today while I wait for Audi Tech to email me results of his diagnostic on the VCDS.

I had these codes come up on the OBD2:
P2102 - Throttle Actuator Control Motor Circuit Low
P0243 - Turbocharger/ Supercharger Wastegate Solenoid A
P0489 - Exhaust Gas Recirculation Control Circuit A Low
P0113 - Intake Air Temperature Sensor 1 Circuit High
P0102 - Mass or Volume Air Flow A Circuit Low

Don't know what all of these mean and what I will need to do to rectify the issues but they make sense as the faults all have electrical implications.

Issue still occurs with new genuine brake light switch.
 
I would check out the 219 relay located in the ECU box. This is the main relay that provides power to the ECU .They do go intermittent and can cause issues. Especially if you have had water leak issues.
An issue with this will stop your car dead, you wouldn't be able to talk to the ECU because it would have no power. The loss of power would cause several different fault codes related to the engine.
You can take the top of the relay and check for dry joints corrosion. The relay is located under the ECU.
If this is your issue I would sack your Audi technician.

http://www.ebay.co.uk/itm/AUDI-VW-S...998601?hash=item2a5a437c49:g:GgwAAOSwd0BVz28g
 
Thanks for your reply. Is the relay in the ECU box located to the left of the brake servo? (top left of engine)
Do you know how this could be linked to the ABS and ESP lights coming on when the car does cut out?
I changed the brake light switch yesterday because of the brake lights being on constantly when the car cuts out and doesn't start. It hasn't fixed the problem and the ABS and ESP lights remain on constantly and affect the drive as if the ABS and ESP really are switched off.
 
The technician did say when the problem occurs and the flashing prnds comes up the engine ECU switches off and doesn't allow his vcds to connect to the car until the flashing prnds disappears. Purely intermittent but has been getting worse. Will have the relay looked at.
 
Looking at the wiring diagram on Elsa Win, The 219 relay feeds the ECU, It also provides a feed to
S286 - Automatic gearbox fuse (for ATF pump run-on)
It provides 12V to the injection pump control unit and also the following
N18 - Exhaust gas recirculation valve
N75 - Charge pressure control solenoid valve
N144 - Electro/hydraulic engine mounting solenoid valve, left
N145 - Electro/hydraulic engine mounting solenoid valve, right
N211 - Throttle butterfly valve

Also feeds a 12V feed to half of the brake switch, which is normally closed.
Without the 12V feed the ECU would see the brake switch as being open so the brake lights would be on.
If it's not the 219 relay there is a small possibility there is an issue with the wiring or the ignition switch.
I would check the 219 relay first, it's located under the ECU.
 
Thanks for the useful information Desertstorm, would replacing the 219 relay take care of the ABS and ESP lights as well or is this a separate issue altogether?
 
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