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Battery draining quickly on my 2019 S5 Coupe, random electrical glitches

0

Mike T. · rep 0 · May 26, 3:48 AM · 1 replies · solved · Question

Vehicle: 2019 Audi S5 Coupe

Hey everyone,

I've been having some really annoying electrical problems with my 2019 Audi S5 Coupe lately. The main issue is that the battery seems to be draining very quickly. If I leave the car parked for more than a couple of days, it's often completely dead or barely has enough juice to start.

On top of that, I've noticed some random electrical glitches. Sometimes the keyless entry doesn't work right away, or the trunk won't open with the button. I've also had the MMI screen flicker once or twice. I had the battery tested at an auto parts store, and they said it was 'weak' but not completely dead, and suggested it might be a parasitic draw.

Has anyone dealt with similar battery drain or electrical ghost issues on their B9 S5? What should I be looking for?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 26, 3:48 AM

0

ClearTheCode admin answer:

Battery drain and intermittent electrical glitches on a 2019 Audi S5 Coupe can be frustrating and often point to a parasitic draw or a failing battery/charging system. Here’s a breakdown of what could be happening:

  1. Failing 12V Battery: Even if the auto parts store said it was 'weak,' a battery that can't hold a charge properly is the most common cause. Modern Audis are very sensitive to voltage fluctuations, and a weak battery can cause a cascade of seemingly unrelated electrical issues. Have the battery professionally load-tested at an Audi dealership or a reputable independent shop, and check its age.
  2. Parasitic Draw: This is when an electrical component continues to draw power even when the car is turned off. Common culprits include:
    • Faulty MMI/Infotainment Module: These modules can sometimes fail to 'sleep' properly.
    • Aftermarket Accessories: Any non-factory installed electronics (dash cams, radar detectors, etc.) can be a source.
    • Door Lock Modules/Keyless Entry System: A malfunctioning module here can stay awake.
    • Trunk Latch/Light: A trunk light staying on or a faulty latch sensor can cause a draw.
    • Gateway Module: This central module can sometimes malfunction and prevent other modules from shutting down.
  3. Alternator Issues: While less likely to cause a parasitic drain, a failing alternator won't properly charge the battery while driving, leading to a discharged battery over time. This would typically trigger a battery warning light on the dash. You might see codes like P0562 (System Voltage Low).
  4. Software Glitches: Sometimes, a software bug in a specific control module can prevent it from entering sleep mode, leading to a draw. A full diagnostic scan might reveal communication errors (e.g., U0100, U0140) or specific module-related codes.

When to see a shop:

  • Immediately: If the battery is consistently dying, it's not only inconvenient but can also put strain on other electrical components. Repeated jump-starts can also be risky.
  • Audi Dealership/Specialist: Diagnosing a parasitic draw is a complex process that requires specialized tools (multimeter, current clamp) and knowledge of Audi's electrical system. A technician will typically perform a 'dark current' test, systematically pulling fuses while monitoring current draw to isolate the faulty circuit or module. They can also check for relevant OBD codes, such as P1602 (Power Supply Terminal 30 Low Voltage), which indicates low battery voltage. This is not a DIY job for most owners and is best left to professionals.
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