2017 Tesla Model S P100D. Vehicle received a paid MCU2 infotainment upgrade (MCU1 to MCU2), which replaced both the center touchscreen computer and the instrument cluster. The original MCU1 architecture used an independent computer for the instrument cluster, providing redundancy. The MCU2 retrofit consolidated both displays onto a single processor with no fallback mode. The first MCU2 replacement unit experienced a touchscreen digitizer failure — touch input stopped responding but the displays remained powered and the instrument cluster continued to function. Tesla replaced it with a second MCU2 unit. The second MCU2 unit has experienced three complete blackout events where both the center display and the instrument cluster simultaneously lose all power — no backlight, no image, no data. One of these events occurred while driving at speed on the road. I lost all instrumentation: speedometer, gear indicator, turn signal feedback, warning lamps, backup camera, and climate controls. I had to pull over with no way to confirm my speed or signal to other drivers. The vehicle remained mechanically drivable — steering, brakes, and motor continued to function. During the recent blackout a few days back, the vehicle had been stored in a closed garage and was not heat-soaked. I have video evidence of the car with both screens completely dead while the vehicle is in gear and moving. A scroll-wheel reboot restored the screens each time. This is my fourth service visit to Tesla for this upgrade. The MCU2 architecture provides no independent fallback display for critical safety information such as speed, gear state, or warning indicators during a processor crash. The prior MCU1 system maintained instrument cluster functionality independently of the infotainment computer.
Tesla Model S loss of power problems
33 of the 3,428 owner complaints about the Tesla Model S describe sudden loss of power, most of them for the 2016 model year.
- owner complaints
- 33
- worst model year
- 2016
- typical mileage
- 33,000
By model year
Often reported together
Power steering loss 8Grinding brakes 3Sudden acceleration 2Overheating 2Screen failure 2Won't shift 1
Trouble codes mentioned
P100D 3
What owners say
I own three 2016 Tesla vehicles with the same known safety defect: two Model S P100D and one Model X P100D, all equipped with the Large Drive Unit (LDU). The component that fails is the rotor coolant seal in the rear drive unit motor. Coolant leaks internally into the motor and inverter, causing bearing wear, corrosion, isolation faults, and eventual complete drive unit failure. The affected drive units are still installed and available for inspection upon request. This defect puts my safety and the safety of others at risk because it can cause sudden loss of propulsion (especially at highway speeds), power reduction, or total drivetrain shutdown, potentially leading to a crash. Coolant in high-voltage areas also raises electrical fault/FIRE risks. The problem is widely reproduced and confirmed: Tesla service centers are familiar with it and replace failed units with updated “-U” revisions that include a coolant bypass. Independent EV shops confirm the exact root cause (rotor seal failure) via encoder inspections showing coolant intrusion and through disassembly. This is a documented pattern failure in all 2012–2020 LDU vehicles. No police or insurance inspections have occurred yet, as no crash or total failure has happened. Tesla is aware of the recurring issue through service records on similar vehicles. Early symptoms before full failure typically include rear motor whining/grinding (especially under load), reduced power warnings, “Rear Drive Unit Fault” messages, and visible coolant on the speed sensor. These can appear gradually. My vehicles have not yet experienced total failure, but the defect is known to be inevitable. I am proactively monitoring encoder sensors. Because this is a systemic design defect affecting thousands of vehicles with clear safety implications, I request the federal safety agency open an investigation and require Tesla to issue a recall for free repairs/replacements on all affected 2012–2020 LDU vehicles.
I own a 2016 Model S P100D equipped with the Large Drive Unit (LDU). The component that fails is the rotor coolant seal in the rear drive unit motor. Coolant leaks internally into the motor and inverter, causing bearing wear, corrosion, isolation faults, and eventual complete drive unit failure. The affected drive units are still installed and available for inspection upon request. This defect puts my safety and the safety of others at risk because it can cause sudden loss of propulsion (especially at highway speeds), power reduction, or total drivetrain shutdown, potentially leading to a crash. Coolant in high-voltage areas also raises electrical fault/fire risks. The problem is widely reproduced and confirmed: Tesla service centers are familiar with it and replace failed units with updated “-U” revisions that include a coolant bypass. Independent EV shops confirm the exact root cause (rotor seal failure) via encoder inspections showing coolant intrusion and through disassembly. This is a documented pattern failure in all 2012–2020 LDU vehicles. No police or insurance inspections have occurred yet, as no crash or total failure has happened. Tesla is aware of the recurring issue through service records on similar vehicles. Early symptoms before full failure typically include rear motor whining/grinding (especially under load), reduced power warnings, “Rear Drive Unit Fault” messages, and visible coolant on the speed sensor. These can appear gradually. My vehicles have not yet experienced total failure, but the defect is known to be inevitable. I am proactively monitoring encoder sensors. Because this is a systemic design defect affecting thousands of vehicles with clear safety implications, I request the federal safety agency open an investigation and require Tesla to issue a recall for free repairs/replacements on all affected 2012–2020 LDU vehicles.
**Incident / Defect Description for the federal safety agency Safety Complaint** **Vehicle Information** - Make: Tesla - Model: Model S - Year: 2014 - VIN: [XXX] - Approximate Mileage: 148,129 miles - Date of Discovery / Failure: 04/23/2026 **Description of the Defect** This vehicle is equipped with Tesla’s Large Drive Unit (LDU / rear drive unit), which was used in the majority of 2012–early 2020 Model S vehicles (RWD and Performance models). The LDU design routes coolant through the hollow rotor shaft. Over time, the rotor seal fails and allows ethylene glycol coolant to leak internally into the motor and inverter. Evidence of this failure is easily visible by removing the rear speed sensor, where blue coolant, corrosion, and debris are present. This is a well-documented design flaw affecting thousands of vehicles. **Consequences of the Defect** Coolant intrusion causes: • Corrosion and rust in the stator windings • Washing out of bearing grease • High-voltage isolation faults • Inverter damage • Complete drive unit failure **Safety Risks** This defect presents an unreasonable risk to motor vehicle safety because: • Drive unit failure can occur suddenly and without warning while driving, resulting in total loss of propulsion. This is especially dangerous on highways, in traffic, or at high speeds. • Coolant inside high-voltage electrical components increases the risk of electrical shorts, arcing, or fire. • Reduced power or complete shutdown can lead to loss of vehicle control and potential crashes. I have experienced complete drive unit failure. Many other owners report identical issues, often between 50,000–120,000 miles. Tesla has not issued a recall despite this being a widespread, predictable design defect. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)
While driving in traffic, the vehicle displayed warnings stating “Unable to drive — Pull over safely.” The vehicle progressively lost power and became unable to propel itself, requiring me to stop in traffic. Additional warnings indicated reduced acceleration and performance. The vehicle remained powered (screens and electronics active) but could no longer drive. Tesla later diagnosed a high-voltage battery failure and provided an estimate for full battery replacement. The sudden loss of propulsion in traffic created a safety hazard because the vehicle could not accelerate or continue moving with traffic.
I am reporting a safety-related defect involving sudden loss of motive power on my 2016 Tesla Model S. During the drivetrain warranty period, the vehicle developed a persistent humming/buzzing noise from the rear drive unit. This noise was documented on video with a timestamp confirming it occurred while the vehicle was under warranty. At the time, there was no loss of performance or warning indicators. Due to the distance to the nearest Tesla service center (approximately 200 miles), the vehicle was not immediately inspected. When I later contacted Tesla Service, the vehicle was approximately three weeks outside the drivetrain warranty. Upon inspection, Tesla advised that the rear drive unit was failing and would require replacement at customer expense. Tesla declined warranty coverage despite evidence that the failure symptoms began during the warranty period. The rear drive unit later catastrophically failed while the vehicle was being driven uphill, resulting in a complete loss of propulsion. Prior to this incident, Tesla service personnel had advised that if the rear motor failed, the front motor would allow the vehicle to operate in a limp mode to reach a safe location. This did not occur. When the failure happened, the vehicle lost all motive power and was unable to maintain position on an incline. The vehicle nearly rolled backward into traffic. Police assistance was required (911 call) to redirect traffic so the vehicle could be rolled backward down the hill to a safe location. A minor child was present in the vehicle at the time. I am aware that failures of rear drive units on 2016–2017 Tesla Model S vehicles related to coolant intrusion have been reported by Tesla service personnel and other owners. This incident demonstrates a serious safety risk involving sudden loss of power and incorrect guidance regarding vehicle behavior during drive unit failure. I believe this represents a safety-related defect warranting investigation.
This is an update to the federal safety agency Complaint #XXX with new safety information. My 2017 Tesla Model S (VIN [XXX] ) has a confirmed high-voltage isolation fault. Tesla replaced the rear drive unit under warranty, but Tesla’s own technician notes now state: “There is a risk of isolation alerts reoccurring during regular driving, use of HVAC system, or DC charging.” “Vehicle may power off due to isolation faults when the air conditioning is used.” This is Tesla acknowledging in writing that the vehicle may shut off during normal driving, even after repair. This presents a serious crash risk. The original failure occurred during Supercharging, with warnings including: • “Electrical system power reduced — vehicle may shut down unexpectedly” • “Vehicle may not restart” • “Air conditioning reduced — DC charging reduced” Tesla reproduced the isolation fault during diagnosis. Even after replacing the rear drive unit, Tesla documented that the isolation defect still exists and prevents a battery health check or DC fast-charge validation. Tesla has attempted to return the vehicle to me in this unsafe condition, while admitting the defect persists. They also stated they may charge storage fees or tow the vehicle, despite the unresolved safety issue. The defect affects the HV bus and can cause loss of propulsion, shutdown during driving, and charging failure. Tesla has not provided numeric test results (megohm isolation readings, insulation tests, or validation data) proving the vehicle is safe. This is an ongoing, manufacturer-confirmed HV isolation defect that can lead to sudden power loss. I request the federal safety agency review Tesla’s handling of this issue and link this filing to Case #XXX. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)
While charging at a Tesla Supercharger, the vehicle began making extremely loud mechanical noises on October 7, 2025, as if something inside the high-voltage system was about to explode. A warning appeared stating “Vehicle may shut down at any time.” A service request was opened the next day. Tesla scheduled the first available appointment nearly a month later, leaving the vehicle unsafe to drive. Before that appointment date, on October 31, 2025, the vehicle completely shut down at a Supercharger and could not be restarted. Tesla Roadside Assistance was dispatched three times before the car was successfully towed to a Tesla Service Center. The failure was diagnosed by the service center as a high-voltage isolation fault logged in the Battery Management System. The problem disables the vehicle suddenly and without warning, posing a serious safety hazard if it occurs while driving. Warning lamps and shutdown messages were present prior to the failure. Tesla service staff stated they could not access diagnostic data until the customer paid for unrelated parts (12-volt battery and A/C compressor). After being challenged, they later retrieved limited battery data proving that the high-voltage system had recorded faults. Tesla has not yet issued a written warranty determination or performed a full battery inspection. The incident demonstrates that a high-voltage battery isolation fault can cause the vehicle to become completely inoperable and may create risk of sudden loss of power while driving or charging. The component (battery pack and related electrical systems) remains in Tesla’s possession and can be inspected upon request.
Premature HV Battery BMS Failure After Tesla Replacement – Safety Risk of Fire and Sudden Power Loss
The vehicle at low speed unexpectedly lost power steering making it impossible to steer. The resistance was greater than on a vehicle without power steering as if the steering mechanism was working to prevent steering. This is the second incident for me -- the first occurring in September, but immediately resolving itself.
Related recalls
No recalls on record for this model year.
Questions about the Tesla Model S loss of power
Which Tesla Model S years have sudden loss of power problems?
The model years with the most reports are 2016 (8 complaints), 2014 (7 complaints) and 2017 (6 complaints).
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