2013 A8 with EPC warning light and multiple DTC's
02-28-2021, 06:24 AM
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2013 A8 with EPC warning light and multiple DTC's
Apologies for first posting this on the D2 platform (my old audi). Just restarted my 2013 A8 after it was sitting outside covered with snow for 2 months. EPC light came on and idle and running were very rough.
Scan shows cylinder 3 and 4 with intermittent misfires adn 7948 cylinder disabling. Multiple other codes came up in multiple other controllers. Checked under the hood and saw no mouse nests or damage to the coil pack wires. Sure sounds like some electrical problem like a bad ground to be affecting so many controllers. Might have water corrosion or rodent damage. I have no idea where to start. Please see my scan log attached.
Scan shows cylinder 3 and 4 with intermittent misfires adn 7948 cylinder disabling. Multiple other codes came up in multiple other controllers. Checked under the hood and saw no mouse nests or damage to the coil pack wires. Sure sounds like some electrical problem like a bad ground to be affecting so many controllers. Might have water corrosion or rodent damage. I have no idea where to start. Please see my scan log attached.
02-28-2021, 07:34 AM
#2
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Voltage too low for starters, that shows in a lot of the codes. Common refrain in Audi light shows. Front of car dirty or covered in snow too.
Put charger on car and/or get new battery--if original it is probably ready for a change anyway. Battery under spare tire. Then clear all codes, module by module--not the global clear, which does not work reliably. Clean front of car.
Then restart, see what happens, and re scan as needed. If you post a scan, best to edit out all the okay modules from the detail to get readers to pay more attention to it.
Put charger on car and/or get new battery--if original it is probably ready for a change anyway. Battery under spare tire. Then clear all codes, module by module--not the global clear, which does not work reliably. Clean front of car.
Then restart, see what happens, and re scan as needed. If you post a scan, best to edit out all the okay modules from the detail to get readers to pay more attention to it.
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DallasDave (02-28-2021)
02-28-2021, 05:08 PM
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Thanks for your patience in looking over my codes. Will take your advice and edit out the no fault ones. I still have the original battery. Sounds like a good starting point. It seems we are married to the dealer as far as battery choices go. Do you know of any cheaper alternatives?
03-01-2021, 06:41 AM
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Many thanks for your expert advice. I charged the battery and cleared all the fault codes for each controller module. No codes returned and the engine and all accessories work fine. I am very disappointed that with such a simple problem as low battery voltage this would not have been glaringly evident from the fault codes. For as sophisticated as the monitoring systems are on the audi a simple fault code stating low battery voltage would have been extremely helpful.
03-01-2021, 06:51 AM
#5
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If you see a code that includes a voltage and it is down at low 12V range or lower with engine running, battery is suspect. Down much into the 11V range not running, same reaction.
You can buy batteries from a variety of sources. Folks get them from NAPA, Walmart, Sears, other decent icar parts stores, etc. You just need the right group size, it should have the typical Audi vent tube attachment point, and be the AGM type. There are at least three sizes/capacities of batteries for D4, but they all fit. My S8 had the smallest; I replaced it with the biggest.
What throws people off sometimes s the "coding" with VCDS. Only the Audi/VARTA ones have the label with a serial/coding number. But as long as you input one of the supported sizes into VCDS (to make the power management system work right) and increase the last number of the battery id number by 1, it will be accepted as valid.
You can buy batteries from a variety of sources. Folks get them from NAPA, Walmart, Sears, other decent icar parts stores, etc. You just need the right group size, it should have the typical Audi vent tube attachment point, and be the AGM type. There are at least three sizes/capacities of batteries for D4, but they all fit. My S8 had the smallest; I replaced it with the biggest.
What throws people off sometimes s the "coding" with VCDS. Only the Audi/VARTA ones have the label with a serial/coding number. But as long as you input one of the supported sizes into VCDS (to make the power management system work right) and increase the last number of the battery id number by 1, it will be accepted as valid.
Last edited by MP4.2+6.0; 03-01-2021 at 06:58 AM.
03-01-2021, 08:59 AM
#6
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What throws people off sometimes s the "coding" with VCDS. Only the Audi/VARTA ones have the label with a serial/coding number. But as long as you input one of the supported sizes into VCDS (to make the power management system work right) and increase the last number of the battery id number by 1, it will be accepted as valid.
Changing a battery used to be simple.If the power is maintained to the system while changing the battery, can we get away with not needing the VCDS to do the swap (like in some crappy garage far from home)? ...or do I need to carry my VCDS with me at all times...?
03-01-2021, 09:06 AM
#7
AudiWorld Senior Member
Lets let the experts chime in, but YES you can just put in a new battery to "get you on your way". But the new battery life will be significantly reduced, since the car will "think" it still has the old unit in it. It must be coded.
BTW, this is the same story with BMW and Mercedes (and probably others). Yes it is a PITA, but I am still on the original battery at five years. Conversely, we are on our third battery in my Son's 2016 Ford Focus (no coding needed, lol). We are on the second battery in my Wife's 2015 Lexus GX460 (no coding here either).
BTW, this is the same story with BMW and Mercedes (and probably others). Yes it is a PITA, but I am still on the original battery at five years. Conversely, we are on our third battery in my Son's 2016 Ford Focus (no coding needed, lol). We are on the second battery in my Wife's 2015 Lexus GX460 (no coding here either).
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03-01-2021, 11:33 AM
#8
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Absolutely horrifying. Changing a battery used to be simple.
If the power is maintained to the system while changing the battery, can we get away with not needing the VCDS to do the swap (like in some crappy garage far from home)? ...or do I need to carry my VCDS with me at all times...?
Changing a battery used to be simple.If the power is maintained to the system while changing the battery, can we get away with not needing the VCDS to do the swap (like in some crappy garage far from home)? ...or do I need to carry my VCDS with me at all times...?
You don't need a charger on car while changing battery. Old tales now 20 years ago. Worst case, you lose date in display more or less and just re enter it. You don't lose the radio memories, the key memories, etc. Post battery change, you have to run windows full down, then full up to restore the one click down/up function. That is a safety feature called anti pinch and it wants to learn the up position to avoid squeezing, hands, necks, kids, pets, etc.
The purpose of coding is to tell the electronics the battery is new and running at full charging capacity. The alternator is linked and then lets it charge up more. Car electronics go through shut down motions if it thinks charge is low, disabling various lower priority things--keyless touch entry goes early for example, maybe back window shade, etc. When it gets desperate, it kills almost everything but core start function and key lights. Thus, helps keep you on road and not stranded, especially for dumb stuff like too many tunes in parking lot/washing car, lights left on inside or out, etc. Thus, if car knows battery is fresh, it permits longer run times on things before starting a shut down sequence of optional loads (called quiesscent modes in Audi speak if you want to search). Audi has never documented what actually happens if you don't code it. My suspicion is car eventually figures it out, just like it does the other direction. But if it is dumbed down logic that just counts ignition cycles and/or total on time, maybe not.
Via VCDS, you can actually see estimated remaining battery life. It might just be a simplistic calculation as mentioned, but is in there. I don't recall exactly where. I just click until I find it--or Google search for it. And yes, VW's have it, Mercs, BMW's, Minis, and so on. D3 had same. Prior Ford, Toyota, etc, typically ended up with AAA or stranded when they crapped out, hard. Real life example, system allowed me to start D3 after leaving parking lights on (stupidly) on D3 for close to 12 hours--on that car ignition off only killed headlights, not all of them if in on position. Got it started and on my way at 9 at night instead of calling AAA and waiting another hour. I realized it as soon as I walked up and both keyless and even the remote were sacrificed in the core keep alive function. Protected battery enough that it recovered fine--often a full discharge by midlife can trash them permanently.
Last edited by MP4.2+6.0; 03-01-2021 at 11:46 AM.
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03-01-2021, 04:19 PM
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Well, sort of neither of these...
You don't need a charger on car while changing battery. Old tales now 20 years ago. Worst case, you lose date in display more or less and just re enter it. You don't lose the radio memories, the key memories, etc. Post battery change, you have to run windows full down, then full up to restore the one click down/up function. That is a safety feature called anti pinch and it wants to learn the up position to avoid squeezing, hands, necks, kids, pets, etc.
The purpose of coding is to tell the electronics the battery is new and running at full charging capacity. The alternator is linked and then lets it charge up more. Car electronics go through shut down motions if it thinks charge is low, disabling various lower priority things--keyless touch entry goes early for example, maybe back window shade, etc. When it gets desperate, it kills almost everything but core start function and key lights. Thus, helps keep you on road and not stranded, especially for dumb stuff like too many tunes in parking lot/washing car, lights left on inside or out, etc. Thus, if car knows battery is fresh, it permits longer run times on things before starting a shut down sequence of optional loads (called quiesscent modes in Audi speak if you want to search). Audi has never documented what actually happens if you don't code it. My suspicion is car eventually figures it out, just like it does the other direction. But if it is dumbed down logic that just counts ignition cycles and/or total on time, maybe not.
Via VCDS, you can actually see estimated remaining battery life. It might just be a simplistic calculation as mentioned, but is in there. I don't recall exactly where. I just click until I find it--or Google search for it. And yes, VW's have it, Mercs, BMW's, Minis, and so on. D3 had same. Prior Ford, Toyota, etc, typically ended up with AAA or stranded when they crapped out, hard. Real life example, system allowed me to start D3 after leaving parking lights on (stupidly) on D3 for close to 12 hours--on that car ignition off only killed headlights, not all of them if in on position. Got it started and on my way at 9 at night instead of calling AAA and waiting another hour. I realized it as soon as I walked up and both keyless and even the remote were sacrificed in the core keep alive function. Protected battery enough that it recovered fine--often a full discharge by midlife can trash them permanently.
You don't need a charger on car while changing battery. Old tales now 20 years ago. Worst case, you lose date in display more or less and just re enter it. You don't lose the radio memories, the key memories, etc. Post battery change, you have to run windows full down, then full up to restore the one click down/up function. That is a safety feature called anti pinch and it wants to learn the up position to avoid squeezing, hands, necks, kids, pets, etc.
The purpose of coding is to tell the electronics the battery is new and running at full charging capacity. The alternator is linked and then lets it charge up more. Car electronics go through shut down motions if it thinks charge is low, disabling various lower priority things--keyless touch entry goes early for example, maybe back window shade, etc. When it gets desperate, it kills almost everything but core start function and key lights. Thus, helps keep you on road and not stranded, especially for dumb stuff like too many tunes in parking lot/washing car, lights left on inside or out, etc. Thus, if car knows battery is fresh, it permits longer run times on things before starting a shut down sequence of optional loads (called quiesscent modes in Audi speak if you want to search). Audi has never documented what actually happens if you don't code it. My suspicion is car eventually figures it out, just like it does the other direction. But if it is dumbed down logic that just counts ignition cycles and/or total on time, maybe not.
Via VCDS, you can actually see estimated remaining battery life. It might just be a simplistic calculation as mentioned, but is in there. I don't recall exactly where. I just click until I find it--or Google search for it. And yes, VW's have it, Mercs, BMW's, Minis, and so on. D3 had same. Prior Ford, Toyota, etc, typically ended up with AAA or stranded when they crapped out, hard. Real life example, system allowed me to start D3 after leaving parking lights on (stupidly) on D3 for close to 12 hours--on that car ignition off only killed headlights, not all of them if in on position. Got it started and on my way at 9 at night instead of calling AAA and waiting another hour. I realized it as soon as I walked up and both keyless and even the remote were sacrificed in the core keep alive function. Protected battery enough that it recovered fine--often a full discharge by midlife can trash them permanently.
03-02-2021, 08:51 AM
#10
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I'm questioning maintaining the voltage during a swap, assuming I'm swapping the battery before the car goes into low power mode. Like, I've got a 2013 with the original battery and I just want to change it without upsetting every system in the car... Does one need to use the VCDS to reset the charging profile of the battery, or does the car figure out that the battery has different charging dynamics?