Hi guys,

Car is as mentioned above.

Recently had an over heating issue and diagnosed to cooling fan modules.

Replaced both cooling fan modules, both temp sensors, checked cooling fans and lubricated. Replaced top coolant hose complete with original bentley new part. Previous had blown off and jubilee clip had come off.

New correct coolant added.

Car was running fine and staying at 90c and fans kicking in.

left it for some time as away and returned to find when sat in traffic, it starts to overheat again. whilst driving at steady speed with air flow car is fine at 90c.
If take it for run and leave to idle, after about 10 minutes, the temp starts creeping up until in the red. fans are coming on but at slow speed intermittently.

now, here is the thing- when switch it off from over heating the fans come on alternately at full speed for about 20 mins .

the other thing I have noticed the car is making a whirring sound whilst switched off, like a pump running.

this whirring sound will start, even if the car has not been run for days and I walk past and try the door to check its locked.

I have tried a couple of independants and spent a small fortune replacing parts, and really gettting to the point of selling because I cant cope with this after 6 months of not being able to use the car properly and spending money.

any advice please

 

Do you have VCDS?

 

Hi,

Thanks for the reply

I should have today or tomorrow, ordered it last week.

Whats your line of thinking?

 

I've been through quite a few issues with a 2004 GT and VCDS helped to pin point the issues.
I have the part numbers for the fans from Audi bypassing the Bentley premium, 3D0959453F left fan and 3D0959453G for the right fan.

 

I am sure vcds will show issue. Let us know.

 

Scanning the ECU's will establish a baseline. Additionally, consider a load test on the left side battery (USA). Electrical management problems can be exacerbated by a seemingly good but weak battery, some of the symptoms hint at that.

Internet diagnosis is difficult. The overheating description suggests a faulty coolant thermostat. Regrettably, the part is not cheap, and than labor.

 

Thanks guys, appreciate the input.

I should have the diagnostic software in a day or 2 and I will be back!


Thanks again.

 

Hi Guys,

I have got the VCDS and apart from all the other random faults related to battery disconnections, this is what its showing in relation to my problems


10 Faults found:
18331 - please check DTC MEMORY of ECU number 2
p1923-008-
18335 - Relay for Aux coolant pump (j496)
p1927 -004- open circuit -intermittant
18080 - coolant fan control 1
p1672 - 004 - open or short to ground - intermitant
18308 - coolant fan control 2
p1900 -004 - open or short to ground - intermitant
18104 - powertrain data bus
18359 - Radiator fan 2 (v177)
p1951 -002 - movement restricted / jammed - intermittant
18358 - radiator fan (v7)
p1950 - 002 - movement restricted / jammed - intermittent
16455 - sensor for ambient air temperature (g17)
p0071 -004 implausible signal - intermittant
19537 - engine temperature too low
03081 - 008 --intermittent
Readiness :0000 1001


Please bear in mind, the fans are not stuck because they run free when they want to and I have checked them both and they are completely free, yes they may have got stuck for some electrical issue but no physical issue with fans.

Also, I have now raised the car from the front considerably to fill the coolant after releasing into container to measure... I believe I managed to get 15 litres max even by lowering and raising the car several times and releasing the lower hose completely.

I have now refilled the car with air pocket removal device made out of a 2 litre bottle cut from the bottom and it has managed to take a considerable amount of more water and the air bubbles took at least an hour to clear.

Could it have had an air lock only ?!!

I have listed the faults exactly as they came up on screen.

Thanks for you help, guys


Hammond

 

 

Clear the faults and take it for a drive. Following that check again to see what faults are re-registered.

 

Very sound advice from Steve. If this is your first scan since you've owned it, the first history can be misleading. Do a global code erase. Drive the car up to the overheat point again, then do a fresh scan. Se what comes back.

 

Hi guys,

Just to update....


Vcds shows fan 1 and 2 movement restricted or jammed intermittent.

But fans run ON AND OFF whilst sat on drive and engine idling happily for half hour without over heating.

NB A.C FAN DOES NOT COME ON WHEN ACTIVATED AND FAULT SAYS NO REFRIGERANT.

When the car is driven and then stops and idle, FANS DO NOT COME ON AT ALL, Even after switch off.

It basically repeats this process. ...

Any ideas before start dismantling car to get to fans AGAIN!

 

You may want to dig deeper into the fan controller feedback path. The fans may come on but the controller must receive the proper feedback signal. The higher the feedback signal the higher the current. High feedback signals a possible stalled fan causing the fault. I'm not sure what this system looks for but normally for fans there is a range of voltage and current feedback which determines fan speed and fault logic. If a fan is stalled current feedback would be high and trigger a fault. Since your fans are running I would look for a high resistance connection somewhere in the wiring or the controller may be misinterpreting the signal. If the controller thinks the fans are stalled the logic may call for the controller to cut the voltage to the fans to prevent a fire.
Just a thought.

 

I had the same errors all be it related to one fan, I changed both using Audi parts (cheaper than Bentley) and it's been fine since.