FrankyD

Been over 2 weeks. Dealer says they cannot even get a status for the part that comes from Germany. Their hands are tied they say!! They suggested I drive without the fan, limited to 3500 limp!! I obviously didn’t accept that especially with the hours of traffic I drive in.

Never had this kind of issue after 10 years of BMW.

Very disappointing.

mplsbrian

Wow, great timing, this issue just hit me last night on the post-work commute, and I managed to make it to the dealer just before the service department closed. (The parts department had closed however, so I won't have a part ETA until they order it today).

Here are some facts that I currently understand:

• The issue is that the fan/fan control module reads a bad voltage to the ECU, making the car think the fan stopped working, even though the radiator fan works. The car goes into limp mode because it believes the fan is broken/not spinning (even though that is not true), as a means to protect the engine from damage (as could occur due to high temps if your fan really wasn't spinning).
• This bad voltage reads happens in certain conditions only -- usually starts on a warm engine. In my case, it happened in traffic while pulling away after the engine start/stop function kicked in.
• The limp condition will go away if you turn the car off and on again -- but will come back if a bad voltage is subsequently received from the fan and/or its control module.
• If you go into a limp mode you should keep an eye on your coolant temps (the temperature LEDs opposite the fuel guage) and your oil temps (measured in degrees and shown in sport view on virtual cockpit) to make sure they are not rising above what you normally see. You should also consider pulling over, getting out, and popping the hood to see if the radiator fan is still turning or not and you will probably find that it is. But if you notice rising temps beyond what is normal (e.g. halfway thru the bars for coolant temps) then DO NOT DRIVE THE CAR. Pull over, pop the hood, and let it cool off for a while -- and if you have far to go flat-bed the thing.
• I've driven three times since the limp mode kicked on last night and it hasn't re-occured.

The above is what I am choosing to do until the fan comes in, I did not let them keep my car. Note that I am not an Audi mechanic and accept no responsibility whatsoever for damage you might incur from choosing to do what I plan to do, but that's my plan. That said if I find that the limp mode condition does come back I might at some point get them to set me up with a loaner, but if I am being honest I am not at this point worried about this issue at all.

millersntx

I say leave the car at the shop and push for a loaner. Just snap a pic of your odometer reading and setup the geo fencing alerts on the MMI app if you're worried about a joy ride. If your warrantied car is sitting on a service aging report, it'll do more to help escalate the issue vs. a back ordered part.

mplsbrian

Update, voicemail from dealer saying fan is a special order from Germany and will take 7-10 business days to arrive (they did not mention if there is a backorder or if that ETA takes one into consideration). Voicemail also reconfirmed that the car should be safe to drive in the meantime but to be cautious / keep an eye on temps if the limp mode re-appears.

Eric Yao

Also happened to my S4 at the end of october, took about 2 weeks for the dealer to receive the fan and replace it.

mplsbrian

Update, drove 8+ hours / 500+ miles over the weekend on a road trip. Limp issue did not reoccur and temps remained normal. In other words I still have no concerns driving it while I wait for the parts to come in.

Out of curiosity, does anyone who has had this done happen to know to what extent the new fan is designed differently? (other than the circuit board or whatever piece of it is causing the voltage issue and resulting engine limp condition that is... AKA is it a different blade design / different fan noise levels / RPMs / different cooling capacity?)

One annoying thing about my previous car (Honda Accord) was that you could clearly hear whenever the radiator fan kicked on/off from inside the cabin. This is something I paid attention to back when test driving the Audi and would be bummed if this new part resulted in more noise than the almost none I hear today.

Glisse

^^

I am sure it will be replaced with the same part. There have been a few instances in Germany, and one or two in the UK, but it does seem to be quite isolated. Most likely an OEM supplier QC issue that they may need to address, rather than an inherent design flaw. Such as BMW's HPFP issues a few years back, which the OP must have been lucky enough to avoid

Your earlier post was excellent, this issue appears to be with the sensor circuit failing to communicate correctly with the Bosch MG ECU. It could also be they have set the voltage range too tight on the ECU, as in your description of when it kicks in there would be some voltage surge through the system. In every report I have read, the fan is still working. And the water temperature is a pretty accurate guide as to whether there is a fan issue. I will say that on an 8 hour road trip of 500 miles at an average of over 60mph, the fan was probably never on. Urban crawl or heat soak following a hard run are more the issue if the fan fails. I think the 3500rpm limit is a general fail-safe when the ECU reads a non-critical fault, it is not specific to this fan issue.

FrankyD

I'm not sure it is exactly the same issue. Limp mode did not go away with restarting the car.

Interestingly, I *did* get affected by the HPFP issue on my 08 335i coupe...! Man do I miss that car.
The S4 is faster, but nowhere near as responsive at the manual 335i on the throttle.

PS: My 2 cents about the throttle lag. It is 100% real. Only a question of a couple of milliseconds, however with the raw power jolt that kicks in, the "power hole" is not only obvious but very difficult to manage.
Easy test: go into a curve at an aggressive but constant speed, and try to hammer it right at the apex. You will see exactly what the "lag/hesitation" people have been discussing in that moment.
That said, I find myself pre-accelerating to compensate, it has become second nature. After a few months, you don't think about it much, except for quick merges here and there.

On the positive side, the finish on this car is excellent. The seats are the best ever. There are many good points.

If Audi resolved the throttle responsiveness issue, the car would be near-perfect.

And included LED lights on both sides of the trunk

Glisse

It's all relative on the throttle response. My first BMW, and first expensive car, was an E36 325i. When they took the straight 6 out to 3 litres, and then worse, added a turbo, I thought they had ruined the engine.

Still, no question the N55/B58 with the ZF8HP feels sweeter on the throttle than the B9 EA837 with ZF8HP. Despite both using twin scroll turbo charger, and the Audi having an advantage in response times with its hot vee arrangement. It is all about throttle maps and economy. But in S mode, post run in cycle (about 1000 miles) it continually frees up and gets more responsive. I have two (S5s), and the difference between the 9 month old vs 3 week old one is significant.

I understand your reticence to drive the car, but a two week delay with still no replacement part in sight is ridiculous. As mplsbrian noted, and as you could confirm, the fan is actually still operating and you can't harm the car driving it. It still goes okay up to 3500rpm. I hope the dealer gave you a decent replacement.

cpippolo

I had the check engine warning light Saturday, revs limited to 3500 rpm, and no auto-stop/start. After a few trips the fault cleared itself and hasn't come back in the last few days, but I scheduled a service appointment to have it checked out. Might be in line for the radiator fan replacement soon. Bummer. Other than not staying put on the overhead view on the right side of the parking camera display (what good is the graphic when you can hear how close you are to objects!), the car has been trouble free over 5500 miles