P0A0D on Mercedes-Benz: How to Diagnose & Fix
High Voltage System Interlock Circuit High
1 Mercedes-Benz model · 1 documented issue · 1 critical
P0A0D on Mercedes-Benz by model: symptoms, diagnosis and fix
Many EQS and EQS SUV owners report frequent 'Battery Malfunction' and 'Malfunction - Towing is not permitted' (Do Not Tow) dashboard messages, in some cases once or twice a month during the first 20,000 miles. The message appears to be a catch-all for several underlying conditions. In milder cases the car still drives and the warning self-clears or resolves with an ignition/12V reset; in severe cases the car refuses to shift into Drive, Neutral or Reverse and is immobilized. A subset of these events trace to a front electric motor 'interlock' fault that prevented the car from being put in Park and required Mercedes to replace the front electric drive motor under warranty. Owners frequently note multiple dealer visits and long parts waits before resolution.
Common Symptoms
- 'Battery Malfunction' message
- 'Do Not Tow' / 'Towing is not permitted' message
- Cannot shift into Drive/Neutral/Reverse
- Vehicle will not go into Park
- Repeated warnings every few weeks
How to Fix
For a transient warning, switch the car off, wait ~5 minutes, then restart; if that fails, a 12V battery disconnect/reset often clears it. Persistent or shift-inhibiting faults require dealer diagnosis: many are resolved with battery/drivetrain software updates (often bundled with the BMS and drivetrain recalls), while a confirmed front-motor interlock fault requires replacement of the front electric drive unit under the EV powertrain warranty.
Sources for this issue (3)
P0A0D 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 P0A0D mean on a Mercedes-Benz?
P0A0D stands for "High Voltage System Interlock Circuit High." The high-voltage interlock circuit voltage is high (typically an open in the HVIL loop). An open interlock causes the HV system to disable for safety. On Mercedes-Benz it is documented across 1 model: EQS.
What are the most common causes of P0A0D?
The most common causes of P0A0D are: Open HV interlock loop (disconnected connector or service plug), Broken interlock wire, Corroded/damaged pins, Control module fault. The specific cause varies by vehicle.
How much does it cost to fix P0A0D on a Mercedes-Benz?
Repair costs vary widely with the root cause and Mercedes-Benz model; each issue on this page carries its own estimate where one is published.
Looking for P0A0D on a different make?
View P0A0D across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.