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2020 Q5 Battery Drain & Start-Stop Not Working - P0562 Code

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Mike T. · rep 0 · May 22, 4:26 AM · 1 replies · solved · Question

Vehicle: 2020 Audi Q5 45 TFSI

Hi all,

I'm having a persistent issue with my 2020 Audi Q5 45 TFSI. Over the past few weeks, the battery seems to be draining much faster than it should. If I leave it parked for more than a day or two, it struggles to start, and sometimes needs a jump. This is a relatively new battery, replaced about 8 months ago.

Coinciding with this, the start-stop system has completely stopped working. I get a message on the dash saying 'Start/Stop System Malfunction' or sometimes it just never engages. I ran a quick OBD scan and pulled a P0562 code, which points to 'System Voltage Low'.

Could these two issues be related? Is it a parasitic draw, or could the alternator be failing to charge the battery properly? Any thoughts on where to start looking? I'm trying to avoid a costly dealership visit if it's something I can troubleshoot myself.

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 4:26 AM

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ClearTheCode admin answer:

The P0562 code (System Voltage Low) and your symptoms of battery drain and a non-functional start-stop system are very much related. The start-stop system is highly sensitive to battery charge and health; if the battery voltage is consistently low, the system will disable itself to prevent further strain.

Potential Causes:

  1. Parasitic Draw: A component in the vehicle is staying active and drawing power even when the car is off. Common culprits include faulty infotainment modules, comfort control modules, or even aftermarket accessories.
  2. Failing Alternator: The alternator might not be charging the battery effectively while the engine is running, leading to a gradual discharge.
  3. Faulty Battery Management System (BMS): The BMS monitors battery health and charge. If it's malfunctioning, it might not be accurately reporting battery status or managing charging correctly.
  4. Battery Issues (even if new): A new battery can still be faulty, or it might not have been properly registered with the BMS after installation, leading to incorrect charging profiles.
  5. Wiring/Connection Problems: Loose or corroded battery terminals or ground straps can impede proper charging and lead to voltage drops.

Troubleshooting Steps:

  1. Test Battery Voltage: Use a multimeter to check the battery voltage when the car is off (should be 12.6V or higher) and when the engine is running (should be 13.5V-14.5V).
  2. Perform a Parasitic Draw Test: This involves connecting a multimeter in series with the battery's negative terminal and monitoring current draw after the car has been asleep for 30-60 minutes. Pull fuses one by one to isolate the circuit causing the draw.
  3. Check Alternator Output: While the engine is running, check the voltage at the battery. If it's not consistently above 13.5V, the alternator might be weak.

When to See a Shop:

  • If you cannot identify the source of a parasitic draw.
  • If the alternator output is consistently low.
  • If the battery was not registered after replacement, as this requires specialized diagnostic tools.
  • If the issue persists after checking basic components, as a faulty BMS or complex electrical fault may require professional diagnosis.
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