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2018 Model 3 Long Range sudden power reduction and 'Vehicle May Not Restart' warning

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Ashley M. · rep 0 · May 22, 5:22 AM · 1 replies · solved · Question

Vehicle: 2018 Tesla Model 3 Long Range

Hey everyone,

I'm having a really concerning issue with my 2018 Tesla Model 3 Long Range. While driving on the highway yesterday, I suddenly felt a significant loss of power. The car wouldn't accelerate properly, and a warning message popped up on the screen saying 'Reduced Motor Performance' followed by 'Vehicle May Not Restart'.

I managed to get it home, but the acceleration is severely limited, almost like it's in a limp mode. I've tried restarting the car a couple of times, but the message persists, and the performance is still way down. The battery charge was around 60% when this happened, so it's not a low battery issue.

Has anyone experienced something similar with their Model 3? What could be causing this, and is it safe to drive it to a service center, or should I arrange for a tow? Any advice would be greatly appreciated!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 5:22 AM

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Hi Sarah,

This is a critical issue that needs immediate attention. A 'Reduced Motor Performance' or 'Vehicle May Not Restart' warning on your 2018 Tesla Model 3 Long Range indicates a significant problem within the high-voltage system or the drive unit itself. Driving with this warning is not recommended and could potentially lead to further damage or leave you stranded.

Here are the potential causes and recommended steps:

  1. High Voltage Battery System Fault: This is a common cause for such warnings. It could be due to a fault within the battery management system (BMS), an issue with a high-voltage contactor, or even a problem with individual battery cells. The system detects an anomaly and limits power to protect itself.
  2. Drive Unit Malfunction: The electric motor or its associated inverter (which converts DC battery power to AC for the motor) could be failing. This would directly impact motor performance and power delivery.
  3. Thermal Management System Issue: Overheating of the battery, motor, or power electronics can trigger these warnings, leading to power reduction to prevent damage.
  4. Low 12V Battery: While less common for this specific message, a failing 12V auxiliary battery can cause a cascade of errors in the high-voltage system, as it powers critical control modules.

What to do:

  • Do Not Drive: Given the 'Vehicle May Not Restart' warning, it is strongly advised not to drive the car. Arrange for a tow to a Tesla Service Center.
  • Check On-Screen Messages: Note any specific error codes or additional details displayed on your Tesla's screen. These can provide valuable diagnostic information to the service technicians.
  • Contact Tesla Service: Use your Tesla app to schedule a service appointment immediately. Clearly describe the warnings and symptoms you're experiencing.

When to see a shop:

  • You should contact Tesla Service immediately. This is not an issue that can be resolved with simple troubleshooting or a software reset. The vehicle's internal diagnostic system will have logged specific fault codes (e.g., VCFRONT_a042, BMS_u018) that only Tesla technicians can properly interpret and address. They have specialized tools and expertise to diagnose and repair high-voltage system components safely.
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