s4 occasionally dies while driving

[///S]

This is the 3rd time this happened. While driving, the whole car shuts down. There is no power or nothing. I can't even turn on the hazards. I have to stop the car and put it in park and then turn on the hazards. In order to restart the car, I have to take the key out and put it back in and it starts. I think the fault code was U0415, i could be wrong but it defiantly started with a U04 _ _

What could this issue be?

[B8 S4]

Thats fucked up, take that shot to the dealer

[lexcruiser]

Car specs? Modded?
Get the car towed to the dealer and get it checked out. NOT safe to drive.. if your car shuts down in the middle of a left turn across on-coming traffic, you're toast.

I had something like this happen with my B6 A4 1.8T that was "chipped." Back when it was actually chipping.. soldering onto the ECU. What we discovered was that one of the soldering points on the chip was bad and it would occasionally lose contact w/ the board hence shutting down the engine.

[///S]

Thats fucked up, take that shot to the dealer

I wish I had a warranty on it. It's a 2011 with 77k on it.. Knowing the dealer, I guarantee they will falsely diagnose it like they have done in the past

[///S]

Car specs? Modded?
Get the car towed to the dealer and get it checked out. NOT safe to drive.. if your car shuts down in the middle of a left turn across on-coming traffic, you're toast.

I had something like this happen with my B6 A4 1.8T that was "chipped." Back when it was actually chipping.. soldering onto the ECU. What we discovered was that one of the soldering points on the chip was bad and it would occasionally lose contact w/ the board hence shutting down the engine.

The only thing done to it is the the roc euro intake. It's stock other than that. 2011 77k miles without the sports diff.

[The Fat Kid]

Try to get someone local to scan it, and start looking for a good independent VW/Audi shop ASAP.

[Kandiru]

I wish I had a warranty on it. It's a 2011 with 77k on it.. Knowing the dealer, I guarantee they will falsely diagnose it like they have done in the past

Then move on to somewhere decent, don't believe that just because you bought the car there you are in any way bound to them.

[Nixon_S4]

The same thing happened on my 2010, right before the mechatronic unit was changed. If you're afraid your dealer will falsely diagnose the issue, send a recommended letter right away to AoA. I'm sure you'll get a very quick answer.

[MrFunk]

Regardless of warranty you need to take it in to a dealer or a reputable mechanic to get diagnosed. It is not safe to drive... if you can't afford the repairs then sell the car... again - it's not safe to drive for you or other people on the road. If the dealer is not proficient then contact AoA and have them send a master tech out to see the car. That's a very serious issue with the car.

[focusaudi]

A corroded or loose battery cable could cause this. Pop the hood.

Sent from my VS986 using Tapatalk

[skiptowncat]

"U" codes are normally communication error codes, not that it really helps any.

[BAHNSTORMER]

Regardless of warranty you need to take it in to a dealer or a reputable mechanic to get diagnosed. It is not safe to drive... if you can't afford the repairs then sell the car... again - it's not safe to drive for you or other people on the road. If the dealer is not proficient then contact AoA and have them send a master tech out to see the car. That's a very serious issue with the car.

So, make the issue someone else's problem.....

[MrFunk]

So, make the issue someone else's problem.....

Trade in to the dealer - they will have to fix before selling...

[Deckdout2]

Mine is starting to do this again. Yesterday it did it 4 times in 10 mins, and again tonight 4-5 times while driving. I'm taking my VAGCOM down now to pull the codes and will report back. This is getting fixed. Other threads I've read about this issue on previous gens have been Crank Position Sensor and another has been Fuel Pump, but Fuel Pump wouldn't have these symptoms.

Lol @ trade it in.......I have a flat, might as well trade it in. Jesus.....

[denako]

Old thread to revive.. but did anything ever come out of this? This has been happening to my 11’ since I was stock in 2015. It’s now 2018 and multiple mods later and it still does it. Never over the winter but in warmer weather about 6-8x a year making it hard to troubleshoot. Sketchy sometimes to be honest, I’ve learned that in order to avoid dying from the car shutting off at highway speeds or into a turn, i pump the gas pedal when it’s not responsive and it keeps it from losing all power.


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[chilort]

Mine was doing something fucky like this and it was the battery. Replaced the battery (with a fancy AutoZone Goldtop) almost a year ago and I've been good-to-go ever since.

[denako]

Mine was doing something fucky like this and it was the battery. Replaced the battery (with a fancy AutoZone Goldtop) almost a year ago and I've been good-to-go ever since.

Interesting. My battery just started discharging after 3 years and seems to be the original still. I’ll change that and see if anything changes.


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[LYKUNO]

Interesting. My battery just started discharging after 3 years and seems to be the original still. I’ll change that and see if anything changes.
Sent from my iPhone using Audizine

Wow, I was going to ask how old your battery was when I saw your earlier post today, but figured that it couldn't have been the original 7 or 8 year old one, especially in a cold weather climate like Chicago. I changed my battery out when it hit 6 years old, not because I was experiencing any issues, but just to avoid the potential for failure at an inconvenient time (like when the wife is driving it somewhere far away). I have to say that the Audi OEM batteries have surprisingly long lives.

Keep us posted on whether a new battery resolves your issue.

[Dannydyn]

What am I missing here? Since when is the battery used while driving? I thought the battery only provides auxiliary power when the engine isn't running. That, and to 'jump-start' the engine upon ignition. Once the engine is started, the battery does nothing (other than being charged by the alternator). So how can a bad battery and/or connection, kill the car while it's running?!?!

[denako]

What am I missing here? Since when is the battery used while driving? I thought the battery only provides auxiliary power when the engine isn't running. That, and to 'jump-start' the engine upon ignition. Once the engine is started, the battery does nothing (other than being charged by the alternator). So how can a bad battery and/or connection, kill the car while it's running?!?!

You've never had a terminal pop off your battery in any former cars? It cuts all power to the car lol. And with your theory, where is the electricity coming from for spark, harness, and everything that uses power?

[Dannydyn]

You've never had a terminal pop off your battery in any former cars? It cuts all power to the car lol.

Thanks Captain...

And with your theory, where is the electricity coming from for spark, harness, and everything that uses power?

Not sure if serious.... but just in case you are:

https://en.wikipedia.org/wiki/Alternator

A car shouldn't just 'die' while *driving*. It *MIGHT* die if you have an already dying/dead battery, you are standing, idling in traffic, and have the A/C, high-beams, stereo blasting, and every other electrical system on. That's where even a good, working alternator won't save you. But a car shouldn't just die while cruising... and on a good working battery to boot (OP didn't say anything about having a bad battery, i.e. problem starting the car). if anything, I'd be looking at the alternator which may have gone bad, and has stopped charging the battery, which in turn cause the car to run 100% off battery alone .....until the battery is drained, and the electrical systems shut off.

[denako]

Thanks Captain...





Not sure if serious.... but just in case you are:

https://en.wikipedia.org/wiki/Alternator

A car shouldn't just 'die' while *driving*. It *MIGHT* die if you have an already dying/dead battery, you are standing, idling in traffic, and have the A/C, high-beams, stereo blasting, and every other electrical system on. That's where even a good, working alternator won't save you. But a car shouldn't just die while cruising... and on a good working battery to boot (OP didn't say anything about having a bad battery, i.e. problem starting the car). if anything, I'd be looking at the alternator which may have gone bad, and has stopped charging the battery, which in turn cause the car to run 100% off battery alone .....until the battery is drained, and the electrical systems shut off.

It was a joke. If the alternator was bad I would've figured it out by now. Like I said above, it happens 6-8x a year randomly and very spread out. If I pump the gas pedal when it goes unresponsive, it picks itself back up after a few seconds. If I don't pump the gas pedal, the whole car shuts off.

[Dannydyn]

It was a joke. If the alternator was bad I would've figured it out by now. Like I said above, it happens 6-8x a year randomly and very spread out. If I pump the gas pedal when it goes unresponsive, it picks itself back up after a few seconds. If I don't pump the gas pedal, the whole car shuts off.

6-8 times a year, randomly means anything but the battery. More like a fault with one of the electric load sensors which throwing off the whole electrical system. A bad battery is pretty much a black and white situation.

[Morritse]

do you have an amp or any aftermarket stereo parts?

[Dannydyn]

do you have an amp or any aftermarket stereo parts?

This ^

[denako]

This ^

I do not. Car has been doing this since 2015 when I was bone stock too. No codes


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[chilort]

Mine was throwing codes (that made no sense) and was going into almost a limp mode (engine running but transmission would go to neutral and all accessories would turn off). It did it while idling in traffic. If I shut the car off it would come back on just fine. It wouldn't do this with the AC off.

Sounds like you may have a different issue.

[TEB]

FWIW, weak/failing batteries on the current generation of vehicles are anything but black and white. Case in point: my wife's Acura MDX. It started fine and then would die 20 seconds later. Start up fine, and die. Over and over. I had it towed to the Acura dealer only for them to tell me it was a bad battery. NFW was I convinced that was the issue, but they put a new battery in and it hasn't had an issue since.

Even weirder with my kids' Honda Pilot: started going into limp mode at completely random times. No issues at all starting. Called AAA, battery tested bad, replace battery -- no issues since. I'm still scratching my head over these two situations.

[chilort]

FWIW, weak/failing batteries on the current generation of vehicles are anything but black and white. Case in point: my wife's Acura MDX. It started fine and then would die 20 seconds later. Start up fine, and die. Over and over. I had it towed to the Acura dealer only for them to tell me it was a bad battery. NFW was I convinced that was the issue, but they put a new battery in and it hasn't had an issue since.

Even weirder with my kids' Honda Pilot: started going into limp mode at completely random times. No issues at all starting. Called AAA, battery tested bad, replace battery -- no issues since. I'm still scratching my head over these two situations.

It has been going on longer than this generation of cars. Trying to describe the interaction of a battery, with voltage that changes with temperature and other factors other than load, and the loads that various electronic boxes put on a battery at different times is often not worth the effort to explain. Many people see a battery as a constant/fixed 12v source. If lucky, they may know a battery isn't really 12 volts. But beyond that, good luck. As a former engineer at Delphi Automotive (off to a different career this days) I had difficulty getting this through to other people who were supposed to also have electrical engineering degrees (like the team that tried to use a voltage divider for a radio display to set a reference voltage only to blow up a bunch of displays because their reference voltage wasn't constant). My experience may be a bit different as I was also on a solar car race team in college where we spent quite a bit of time with batteries. Eventually, I gave up. And I usually just give up as I did a couple posts up.

TL:DR -- try the battery because you'll be surprised at what all can go wrong and the wonky ways it'll happen with a bad or failing battery. And of all the things to replace, a battery isn't that expensive and at 4+ years old it probably won't be long anyway.

[Dannydyn]

FWIW, weak/failing batteries on the current generation of vehicles are anything but black and white. Case in point: my wife's Acura MDX. It started fine and then would die 20 seconds later. Start up fine, and die. Over and over. I had it towed to the Acura dealer only for them to tell me it was a bad battery. NFW was I convinced that was the issue, but they put a new battery in and it hasn't had an issue since.

Even weirder with my kids' Honda Pilot: started going into limp mode at completely random times. No issues at all starting. Called AAA, battery tested bad, replace battery -- no issues since. I'm still scratching my head over these two situations.

When you can diagnose something as quickly and easily as with a voltage meter (=bad battery), it's black and white.

[TEB]

When you can diagnose something as quickly and easily as with a voltage meter (=bad battery), it's black and white.

In both cases, the batteries had tested good within a month or two of the final problems. This lead me to erroneously rule out the batteries initially. I understand your point, though. At any rate, this experience has led to a running joke around our house of blaming any issue on the battery.

[Dannydyn]

In both cases, the batteries had tested good within a month or two of the final problems. This lead me to erroneously rule out the batteries initially. I understand your point, though. At any rate, this experience has led to a running joke around our house of blaming any issue on the battery.

well, glad to hear it worked out in the end.

[TEB]

It has been going on longer than this generation of cars. Trying to describe the interaction of a battery, with voltage that changes with temperature and other factors other than load, and the loads that various electronic boxes put on a battery at different times is often not worth the effort to explain. Many people see a battery as a constant/fixed 12v source. If lucky, they may know a battery isn't really 12 volts. But beyond that, good luck. As a former engineer at Delphi Automotive (off to a different career this days) I had difficulty getting this through to other people who were supposed to also have electrical engineering degrees (like the team that tried to use a voltage divider for a radio display to set a reference voltage only to blow up a bunch of displays because their reference voltage wasn't constant). My experience may be a bit different as I was also on a solar car race team in college where we spent quite a bit of time with batteries. Eventually, I gave up. And I usually just give up as I did a couple posts up.

TL:DR -- try the battery because you'll be surprised at what all can go wrong and the wonky ways it'll happen with a bad or failing battery. And of all the things to replace, a battery isn't that expensive and at 4+ years old it probably won't be long anyway.

Yeah, I'm sure this started happening to some degree with the first ECUs. As electronics have gotten more and more integrated, it's getting worse. My philosophy has always been to not mess with batteries -- always replace at the first sign of weakness. That almost always used to be a slow turn-over, now I'm not sure exactly what to attribute. BTW, I'm a GMI Engineering grad -- I know many people who work at Delphi. I went ME for a reason, lol.

[chilort]

When you can diagnose something as quickly and easily as with a voltage meter (=bad battery), it's black and white.

There's a reason even Autozone uses a load test rather than just a volt meter.

[Dannydyn]

I meant it in a more loosly way. But sure, whatever to it takes.

[bhvrdr]

Yeah, I'm sure this started happening to some degree with the first ECUs. As electronics have gotten more and more integrated, it's getting worse. My philosophy has always been to not mess with batteries -- always replace at the first sign of weakness. That almost always used to be a slow turn-over, now I'm not sure exactly what to attribute. BTW, I'm a GMI Engineering grad -- I know many people who work at Delphi. I went ME for a reason, lol.

You and chilort really mirror some experiences ive had on late model cars with battery issues.

On my SS i went to start it one day and it fired up fine no problem but id get stability control faults, abs faults and all instruments worked perfectly including comfort features like stereo EXCEPT the tachometer was completely non functional.

The car drives fine and revs hard as hell then all the sudden you get partial cylinders deactivated and misfires. Car still runs and starts up multiple times fine.

So i post about it and literally like instantly 5 replies saying "oh yeah thats exactly what happens when the battery gets old." Im like wtf? Replace the battery and all is perfect.

The ecu in these cars are interesting. So many weird maps in the ecu rely on battery voltage monitors. Even timing maps. It may have been back in the 80s cars "ran off the alternator" but now they are so interdependent it seems.

Mike

[$nooze]

I had this issue too, similarly to the poster above whom had to pump the gas pedal I have to hit clutch until the rpms of the dying engine drop to about ~1000 then pop clutch for it to start. Nothing else gets it going. I do have the battery meter enabled within the mmi unit and it always shows 100% when I check. Could there potentially be another reason why it would lose response from the gas pedal but remain powered everywhere else?

[juniorcruzer]

if your battery has not been replaced in ~5 years, and having a weird electrical issue, just replace it. You are working on borrowed time for the battery even if it still tested good. Been burned to many times over the years for batteries causing issues, or leaving me completely stranded when it failed all of a sudden. It was always not long after them hitting the 5-6 year mark.

Jon