U15AC on 2021 Audi e-tron — Signal Damping Log - Malfunction
1 vehicles · 1 makes
How to diagnose and fix U15AC: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Audi e-tron · 2021–2021
Audi TSB 2061788/2 covers model-year 2021 e-tron quattro and e-tron Sportback vehicles with specified AC/DC charging interruptions, charging-flap operation problems, or an app request for auxiliary heating that does not pre-heat the vehicle when matching DTCs are stored in high-voltage battery charger control module J1050. Audi attributes the documented condition to onboard-charger software and identifies old software level 0070, not a proven failed charger module.
Common Symptoms
- AC or DC charging is interrupted
- DC charging does not start or stops at some stations
- Charging-flap button is inoperative or the flap does not open
- Auxiliary heating is activated through the app but the vehicle does not pre-heat
How to Fix
Record whether the failure is AC, DC or station-specific and have J1050 scanned before parts. If the vehicle has the matching condition and software level 0070, Audi directs an SVM update to software 0079 or higher. After the update, reproduce the concern and follow the guided test plan for any new active DTC. Do not infer hardware failure merely because one charging mode works, and do not order the former charger, 12-volt battery, relay, meter or portable EVSE from this card.
Owner tips & cautions
- TipBring the failed station, date and charging mode to the diagnosis and ask for the J1050 software level and full DTC list before authorizing hardware.
Sources for this issue (1)
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U15AC code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does U15AC mean?
U15AC stands for "Signal Damping Log - Malfunction." A charger-internal diagnostic fault relating to the signal damping log used by the powerline communication (PLC) path in the charging system. Audi lists DTC U15AC00 ("Signal damping log malfunction", also rendered "Signal damping log fault") in TSBs 2061788 and 2062631 as one of the codes stored in high-voltage battery charger J1050 on 2020-2021 e-tron quattro and e-tron Sportback. Audi explicitly attributes these entries to a diagnosis issue in the onboard-charger software (levels 0070/0079/0081/0088) - they are documented "ghost" DTCs, not evidence of failed charging hardware.
What are the most common causes of U15AC?
The most common causes of U15AC are: Onboard-charger software diagnosis fault - Audi's documented remedy is the OBC software update via SVM (TSB 2062631), Communication signal degradation on the DC charging PLC path, Charging station-side communication quality issue. The specific cause varies by vehicle.
How much does it cost to fix U15AC?
Repair costs vary widely depending on the root cause and vehicle.
Which vehicles are affected by U15AC?
Au7o has documented U15AC across 1 vehicle models from 1 manufacturers: Audi.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.