Key fob battery woes

[Gordyzero]

my 2019 S4 19,000 miles ..it's been in the garage for a while. I had the day off so I went for a ride . As soon as I got where I was going I had the key battery low message. No big deal I buy a new battery.. The message won't go away. Key fob works fine. At this point I am 70 miles away from home with multiple stops to make. I keep getting the battery low warning on start up . So .. I buy MORE batteries 3 new Batteries later. Message won't go away. I tried my other Key fob when I got home even swapped batteries. No issue with the other fob regardless of what battery I use. Could this fob be defective all of a sudden ? Do I need to clear that code for that key ? Any ideas , ,? Thanks and happy new years .

[Spike Spiegel]

my 2019 S4 19,000 miles ..it's been in the garage for a while. I had the day off so I went for a ride . As soon as I got where I was going I had the key battery low message. No big deal I buy a new battery.. The message won't go away. Key fob works fine. At this point I am 70 miles away from home with multiple stops to make. I keep getting the battery low warning on start up . So .. I buy MORE batteries 3 new Batteries later. Message won't go away. I tried my other Key fob when I got home even swapped batteries. No issue with the other fob regardless of what battery I use. Could this fob be defective all of a sudden ? Do I need to clear that code for that key ? Any ideas , ,? Thanks and happy new years .

I'd say you should try clearing the code and see what happens. If your key was defective I imagine it wouldn't be able to complete the handshake to start your car in the first place since the changing of the batteries. Can't imagine the defectiveness would only be regarding that low battery warning after you changed batteries. Also, what up fellow New Englander.


Best,


Space Cowboy

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2019 Daytona Gray RS 3 | Instagram: SPCECB

[Gordyzero]

That's what I am doing next. I do this for a living. I never have a problem like this. I've encountered codes for defective key on other makes and models that have led me down other roads. But .. ugh . I am new to the B9 .. learning curve in progress .Thanks Space Cowboy waiting on snow here in Vermont. I wanted to get in one more ride... and DING battery low.. Damnit.

[chris.miller]

That's what I am doing next. I do this for a living. I never have a problem like this. I've encountered codes for defective key on other makes and models that have led me down other roads. But .. ugh . I am new to the B9 .. learning curve in progress .Thanks Space Cowboy waiting on snow here in Vermont. I wanted to get in one more ride... and DING battery low.. Damnit.

Have aftermarket remote start?

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[Gordyzero]

No sir. Completely stock ! No mods . no OBD eleven " apps " no vag com long coding. NOTHING.

[qcrazy]

I was having trouble getting my car to unlock recently. Didn't think much about it, just made sure the key was closer to the car when I locked/unlocked it. It was slowly getting worse, just starting to get annoying. Then one day I started it up, and the low key battery light came on. AH HA! Why didn't I think of that? Put in a new battery, all is back to normal.

Were/are you having any issues with the car unlocking? If not, perhaps it something external to the car causing an issue.

Is it happening in a certain location or everywhere? Anything installed in your car that could be interfering with the signal? iPad, rear screen, or anything like that? What happens if you don't have your phone with you? Just throwing ideas out there. Your issue doesn't sound like a key battery problem.

[Gordyzero]

Never had any trouble with it. Even when the battery low message came on . Fob works fine. The message isn't going away , but only with that fob. My spare fob. No prob. Idk.. I wanted to post a thread. I can't be alone on this. I've never had to clear a code after changing a fob battery.. maybe this will be the first time 🤔

[qcrazy]

Sounds like a bad key.

I had zero issues after replacing the key battery. Just replaced the battery and everything went back to normal.

[Gordyzero]

Could be. I'm curious how this is a sudden problem. The car sits in a garage. The keys sit in a drawer. It's worth mentioning. I'll follow up if I ever have a solid answer.

[Gordyzero]

So . The car has sat in my garage since this happened new years day. I went out with key 2 no trouble no message. I went down to the garage with key 1 . BOOP key fob battery message is back. I scanned the car after every lock / unock & key cycle option possible. Code was still there since it was generated on New years day, and that was the LAST time the data log was time stamped , even after the code was generated tonight ( at least in the driver display ) .. It just doesn't seem to recognize the battery. I drove it half the day on new years after the new battery. Low battery message never went away. I cleared the code tonight and so far the message is gone. If this is the way to solve it . How stupid. Are we down to this now,?? That even a key fob battery needs a code clearing , bahahaha . It works so far. 4 key cycles later no fob battery warning. I'll follow up if the key fob is the problem. But so far. I think ... I THINK it's solved.

[Longtallsally]

Ironically both fob batteries tanked at the same time in ‘19. I’ve not been driving the car much but when I was about to head on a decent trip, I got that warning and even had to use the pop out key a couple times to open the door. It started fine putting the key by phone charger. When I got home swapped both batteries and zero issues. Maybe there was a lot of data for the key to capture?

[Gordyzero]

interesting... the lack of continuity with this stuff. Both my keys worked fine even the one with a " low battery " . Normally I would just say " Because Audi " and shrug it off. It's no big deal until you are somewhere and your $65000.00 car is a flower pot over a $3 battery that was just fine 10 minutes ago. That's my only concern. My new GTI did that to me out of nowhere. Car wouldn't start. Stranded. Granted It was a GTI. Half the cost of an S4.. but. .. ya know. What if . Going forward I'm changing my batteries every Season.

[Longtallsally]

interesting... the lack of continuity with this stuff. Both my keys worked fine even the one with a " low battery " . Normally I would just say " Because Audi " and shrug it off. It's no big deal until you are somewhere and your $65000.00 car is a flower pot over a $3 battery that was just fine 10 minutes ago. That's my only concern. My new GTI did that to me out of nowhere. Car wouldn't start. Stranded. Granted It was a GTI. Half the cost of an S4.. but. .. ya know. What if . Going forward I'm changing my batteries every Season.

It’s hard to argue as there are times with see jermahn cahz when they do whatever they want, when they want. I set up via OBD Eleven to have the car unlock when I approach. Works about, mmm, 40-50% of the time.

Of note on my batteries, I never got a low battery warning- it went straight to “key not recognized”. I wasn’t going to make a big deal o it unless the battery replacement didn’t work. It did, so meh. I’ll just chalk a lot of this stuff up to there is just too much code running at the same time and sometimes the processors can’t keep up with the requests.

[SHCKR]

Batteries are like $5 for 10-pack if you buy them in advance online. Just buy a pack, throw into a random cubby in your car -winning.

B9S4 all packages

[Gordyzero]

It’s hard to argue as there are times with see jermahn cahz when they do whatever they want, when they want. I set up via OBD Eleven to have the car unlock when I approach. Works about, mmm, 40-50% of the time.

Of note on my batteries, I never got a low battery warning- it went straight to “key not recognized”. I wasn’t going to make a big deal o it unless the battery replacement didn’t work. It did, so meh. I’ll just chalk a lot of this stuff up to there is just too much code running at the same time and sometimes the processors can’t keep up with the requests.

Key not recognized .... out of nowhere . I love it. These cars earn their reputation. As Audi lover we laugh at this shit. My brother bought one ( Ford driver ) liked it because it was fast. When he found out you needed a vag com or Obd eleven to do the rear brakes and reset service reminders. He traded it, all salty about it still 4 years later.

I'm not sure why the key fobs are this bad at telling the truth. This is exactly the crap that happens every time you let these cars sit . Every time I leave one sitting in the garage for a few weeks it comes back haunted. Millions of lines of code + low voltage = anything could go wrong. The most trouble free S4 I ever had I drove it everyday until I ruined the value. , never changed a key fob battery , LOL

- - - Updated - - -

Batteries are like $5 for 10-pack of you buy them in advance online. Just buy a pack, throw into a random cubby in your car -winning.

B9S4 all packages

I just stocked up

[Longtallsally]

Key not recognized .... out of nowhere . I love it. These cars earn their reputation. As Audi lover we laugh at this shit. My brother bought one ( Ford driver ) liked it because it was fast. When he found out you needed a vag com or Obd eleven to do the rear brakes and reset service reminders. He traded it, all salty about it still 4 years later.

I'm not sure why the key fobs are this bad at telling the truth. This is exactly the crap that happens every time you let these cars sit . Every time I leave one sitting in the garage for a few weeks it comes back haunted. Millions of lines of code + low voltage = anything could go wrong. The most trouble free S4 I ever had I drove it everyday until I ruined the value. , never changed a key fob battery , LOL

German car ownership. They have always been “cutting edge” so there is a need to go into ownership with a bit of an open mind. I remember from my E30 BMW days, ‘Mericans were ticked that the head unit was a dumb receiver and there was a separate amp to drive the speakers as it seemingly was more difficult to wire up a new head unit.

Back on keys, I went to take one of the children of the corn to school this morning and walked to the garage where not only did the car not recognize me approaching and didn’t Auto Unlock, it didn’t even recognize my hand touching the door handle and I had to use the key on to unlock the doors (oh the horror!) and the door handle lights didn’t come on then either. It was pretty cold last night and I’m not driving the car very much or for long drives generally, so I’m certain this was some battery preservation deal. And then after dropping off the kid, it again didn’t unlock on approach, but unlocked when I touched the handle.

I think it’s kinda funny. After driving a Jeep and all it’s idiosyncrasies, none of this stuff gets me riled up.

[Sturn992]

I have had the same issue on my 2019 S4 I have to use the secondary key. I am tuned so I won’t be able to take it in till I go in for my next service and have it sorted out then. I think the keys just go bad. The dealer said they will only take energizer lithium batteries but when they swapped it out with their batteries it did not help. If you find an at home fix and share it I’ll Venmo you beer money lol

[Gordyzero]

German car ownership. They have always been “cutting edge” so there is a need to go into ownership with a bit of an open mind. I remember from my E30 BMW days, ‘Mericans were ticked that the head unit was a dumb receiver and there was a separate amp to drive the speakers as it seemingly was more difficult to wire up a new head unit.

Back on keys, I went to take one of the children of the corn to school this morning and walked to the garage where not only did the car not recognize me approaching and didn’t Auto Unlock, it didn’t even recognize my hand touching the door handle and I had to use the key on to unlock the doors (oh the horror!) and the door handle lights didn’t come on then either. It was pretty cold last night and I’m not driving the car very much or for long drives generally, so I’m certain this was some battery preservation deal. And then after dropping off the kid, it again didn’t unlock on approach, but unlocked when I touched the handle.

I think it’s kinda funny. After driving a Jeep and all it’s idiosyncrasies, none of this stuff gets me riled up.

So true if you think owning a German car is a trouble free turn key experience , but lets admit it we buy these things because when they are working at their peak of awesome. You cannot find a more rewarding experience . I was so tired of my Last S4 gripping my wallet with both hands as it aged.I bought a new 2017 GTI sport . I was so bored with that car .. I bought a new 2019 Golf R... still missed all things Audi. Then .. I went back to my abuser.. And here I am actually in love with what I drive again. But about your current situation -WAIT.. this just happened. ? BTW.. I like the throw back E30 story ! Anyway back to the key .. Here is my theory. Until you clear the code. I think one of the many modules has it's middle finger up over that key. Have you cleared the key fob battery code since replacing the battery ?

[Gordyzero]

I have had the same issue on my 2019 S4 I have to use the secondary key. I am tuned so I won’t be able to take it in till I go in for my next service and have it sorted out then. I think the keys just go bad. The dealer said they will only take energizer lithium batteries but when they swapped it out with their batteries it did not help. If you find an at home fix and share it I’ll Venmo you beer money lol

Let us know what happens. I am happy I started this thread . Proof something is being very German here. Let's see if we can document an actual solution.

[combover0808]

Stumbled onto this thread after changing my turbos and car sat for 8 months. Key fob won’t unlock the door and I have to push the start button, wait for “key not recognized” message then hold the key up to the area beside the radio and then the car starts. New battery in key fob did not help. Anyone find a solution to this?


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[combover0808]

So true if you think owning a German car is a trouble free turn key experience , but lets admit it we buy these things because when they are working at their peak of awesome. You cannot find a more rewarding experience . I was so tired of my Last S4 gripping my wallet with both hands as it aged.I bought a new 2017 GTI sport . I was so bored with that car .. I bought a new 2019 Golf R... still missed all things Audi. Then .. I went back to my abuser.. And here I am actually in love with what I drive again. But about your current situation -WAIT.. this just happened. ? BTW.. I like the throw back E30 story ! Anyway back to the key .. Here is my theory. Until you clear the code. I think one of the many modules has it's middle finger up over that key. Have you cleared the key fob battery code since replacing the battery ?

Any idea what module controls the key fobs? I’m trying to use a regular OTC scan tool to clear the codes


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[Longtallsally]

So true if you think owning a German car is a trouble free turn key experience , but lets admit it we buy these things because when they are working at their peak of awesome. You cannot find a more rewarding experience . I was so tired of my Last S4 gripping my wallet with both hands as it aged.I bought a new 2017 GTI sport . I was so bored with that car .. I bought a new 2019 Golf R... still missed all things Audi. Then .. I went back to my abuser.. And here I am actually in love with what I drive again. But about your current situation -WAIT.. this just happened. ? BTW.. I like the throw back E30 story ! Anyway back to the key .. Here is my theory. Until you clear the code. I think one of the many modules has it's middle finger up over that key. Have you cleared the key fob battery code since replacing the battery ?

I’ll hook the OBD Eleven up and see if the code stuck and needs to be cleared. And this morning it did the same thing. It actually annoyed me as my hands were kinda full, so I expected it to unlock when I touched the handle. But I’m at 20k, and I’ll bring it up with the dealer when I take it in for service...

[Gordyzero]

Any idea what module controls the key fobs? I’m trying to use a regular OTC scan tool to clear the codes


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comfort system

[Gordyzero]

I’ll hook the OBD Eleven up and see if the code stuck and needs to be cleared. And this morning it did the same thing. It actually annoyed me as my hands were kinda full, so I expected it to unlock when I touched the handle. But I’m at 20k, and I’ll bring it up with the dealer when I take it in for service...

now THAT would piss me off. My car just rolled over 19,000 miles. Funny the timing. Your car may also need a software update. My dealer did it in October when I had them flush my brake fluid my brake fluid for the 20k, I did the rest of the 20K service myself . The software update..they had no idea what it did. ECM sfotware 24 FG. Maybe your dealer can tell you what it does.

[Longtallsally]

And today as I was loading the Jeep to head out and go off reading for the day with the S4 key in my pocket as I walked by it in the garage? It unlocked... Now you gotta find that funny.

[Gordyzero]

[QUOTE=Longtallsally;14419199]And today as I was loading the Jeep to head out and go off reading for the day with the S4 key in my pocket as I walked by it in the garage? It unlocked... Now you gotta find that funny.[/QUOTEof

OF COURSE it works when you don't need it . BAHAHA.. if it was raining and you had your arms full. Nothing would happen. Time to flush those codes . Your dealer will probably blame your obd eleven and want to charger you something stupid. I would remove that obd eleven app and clear all your module coeds if I was in your situation. This won't be funny in another few weeks. That shit gets old fast.

[billyjohnny]

So strange.... I had the exact same problem yesterday in my ‘19 S4. I started the car and got the low key fob battery warning. I tried changing the key fob battery three times and the warning wouldn’t go away. I ended up clearing the code with OBD11. It hasn’t come up since then.

[Longtallsally]

OF COURSE it works when you don't need it . BAHAHA.. if it was raining and you had your arms full. Nothing would happen. Time to flush those codes . Your dealer will probably blame your obd eleven and want to charger you something stupid. I would remove that obd eleven app and clear all your module coeds if I was in your situation. This won't be funny in another few weeks. That shit gets old fast.

Nah I’m not worried about it. I already had the OBD Eleven at the first service and they didn’t see anything. I really got it for some tiny little things and for diagnostics when it eventually goes out of warranty. The only stuff I’ve done are things like add the gear I’m in even in “drive” and mirroring the brightness of the infotainment screen to the cluster. About the only other thing I’ve done is to add the “Scandanavian driving lights” in keeping the tail lights on all the time. I’m not trying to turn off start stop, or fool the exhaust valves into being open all the time (I actually like that stuff) or anything else that takes serious effort.

About the only change I’m planning on at some point is to change the tire pressure readings from passive to active by putting the sensors in the wheels and the coding associated with that. As that is an OEM option on the RS machines, it shouldn’t be a big deal, but I’ve admittedly been a little chicken to do it thus far.

I’m still going to scan for codes and see what comes up. I’ll report back when I do...

[Gordyzero]

So strange.... I had the exact same problem yesterday in my ‘19 S4. I started the car and got the low key fob battery warning. I tried changing the key fob battery three times and the warning wouldn’t go away. I ended up clearing the code with OBD11. It hasn’t come up since then.

You lived my exact scenario. Please let us know if that code comes back before it should . My S4 is hiding in the garage till spring . So I can't test my theory. But I do believe this is the solution. I'm glad to see this is becoming a pattern we have identified , and may have a solution for. My dealers service department won't even talk to you unless they know you're spending money. If it wasn't for the guys in the parts department. I would be driving a Lexus.

[Gordyzero]

I'm very apprehensive to go down the long code rabbit hole. But OBD eleven does make it easy with Apps. Vag com just became too expensive for me to keep up with. OBD eleven offers allot for that price point. It's a must have. I must say about the tire pressure readings . I never knew that and was always disappointed I couldn't see the actual tire pressure. My light came on @ 70MPH... I had 10 miles till the next exit. Not a good feeling. Of course you need a RS to see tire pressure. Or a stack of parts and long code.. You gotta love it. This is why I keep a Corolla in the driveway. Simplicity . Just turn the key.

[Gordyzero]

Thanks to everyone for the valuable input here !!! We've covered just about every scenario, You don't get this kind of feedback on the Vortex. Always some prick wants to argue.

[Longtallsally]

I'm very apprehensive to go down the long code rabbit hole. But OBD eleven does make it easy with Apps. Vag com just became too expensive for me to keep up with. OBD eleven offers allot for that price point. It's a must have. I must say about the tire pressure readings . I never knew that and was always disappointed I couldn't see the actual tire pressure. My light came on @ 70MPH... I had 10 miles till the next exit. Not a good feeling. Of course you need a RS to see tire pressure. Or a stack of parts and long code.. You gotta love it. This is why I keep a Corolla in the driveway. Simplicity . Just turn the key.

Going a little off topic, if you want to do the switch from passive to active TPMS, there is a really good thread here (I may have even started it- I can’t remember) with vendors and everything on how to do it. Bottom line, it’s not as expensive as you might think: remember, the cluster is a full on screen, so it’s nothing more than the monitors being installed in the wheels, a controller, and some code.

[Sturn992]

Resolution for mine was a stuck low voltage code. Didn’t show up on my $300 scanner from ECS but OBD11 found it and cleared it no problem. Thank you all for helping.

[Gordyzero]

So , if this really is the fix . Can you imagine the Audi Quality surveys that are being bombed over something this stupid ? This is the shit that brings down brand reliability in the eyes of the average consumer. Basically. Audi wants you to bring your car to them for everything. Up next . Washer fluid low error code .

[Longtallsally]

Well I finally got the chance to pull and clear all the codes. Sheesh! 25 total! Nothing to be worried about as they were all ones from driving in the snow a while back and the sensors all got covered up, so I went through each of them. There were no codes associated with the key, but I thought a couple convenience ones. I cleared all of them and earlier when I walked by the car, sure enough it unlocked. Meh, who cares, I still love the car and I still consider it stone reliable as none of that stuff triggered a CEL, and I suspect there more for analysis should another issue arise with those systems.

I’m calling it an idiosyncrasy of the car and a function of my initial analysis which is 2 fold: too much going on for the processor(s), and the main battery not being in full tip top shape due to how rarely I drive these days.

[Gordyzero]

Funny there was no key fob codes. But . Meh. Because Audi. As you pointed out. too much code. Not enough driving. A recipe for not enough voltage and here comes a haunted car. I am always surprised of how much trouble can be created by a car sitting in a low voltage state. Just because it has enough battery to start the engine, doesn't mean all the modules are happy about it. Good lesson to learn. Drive it or keep it charged. And if all else fails. Sweep away those b.s codes , it might just be the fix. I checked my car the other night. cycled the key a couple time with the fob that was a problem a few weeks back. NO CODE , still.

[Gordyzero]

Annnd I'm back with another update. I made it almost 8 months , same key fob ate another battery. That was a new Panasonic Battery that had years to go before it's expiration date. And these batteries were sitting in a desk drawer inside a house. No extreme temperatures , next to my key fobs. So . In closing. Do yourself a favor . Throw a new key fob battery in every 6 months . Conclusion. The fobs just eat batteries. And if you leave your fob in your car for example in your garage. Forget it . Probably dead in 3 months. I find it funny Audi or no company that I'm aware of has a rechargeable key fob. WTF . Imagine just throwing your car keys in fob charger location as you drive ? If only wireless charging technology existed ....

[SHCKR]

Annnd I'm back with another update. I made it almost 8 months , same key fob ate another battery. That was a new Panasonic Battery that had years to go before it's expiration date. And these batteries were sitting in a desk drawer inside a house. No extreme temperatures , next to my key fobs. So . In closing. Do yourself a favor . Throw a new key fob battery in every 6 months . Conclusion. The fobs just eat batteries. And if you leave your fob in your car for example in your garage. Forget it . Probably dead in 3 months. I find it funny Audi or no company that I'm aware of has a rechargeable key fob. WTF . Imagine just throwing your car keys in fob charger location as you drive ? If only wireless charging technology existed ....

That works for us, men, but every woman I know keeps her keys in her purse.. Meaning rechargeable ones would die what, weekly?

[Gordyzero]

That works for us, men, but every woman I know keeps her keys in her purse.. Meaning rechargeable ones would die what, weekly?

That's a great point . Women would be sure to keep it charged if they could update their Instagram and Facebook with the key fob. Maybe a selfie filter ?

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[RickNY]

I find it funny Audi or no company that I'm aware of has a rechargeable key fob.

LOL.. Our old 2010 Nissan Maxima had a rechargeable fob and a corresponding place in the dash to stick it in to charge it..