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Reduced Power and Whining Noise from Drive Unit on 2019 Model S

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Mike T. · rep 0 · May 22, 5:22 AM · 1 replies · solved · Question

Vehicle: 2019 Tesla Model S Long Range

Hey everyone,

I've been experiencing a concerning issue with my 2019 Tesla Model S Long Range. Over the past few days, I've noticed a significant reduction in power, especially when accelerating from a stop or trying to pass on the highway. It feels like the car just isn't delivering the torque it used to.

Compounding this, there's a distinct whining noise coming from what sounds like the rear drive unit. It's most noticeable between 30-60 mph and changes pitch with acceleration. I haven't seen any immediate warning lights on the dash, but the performance drop is undeniable.

Has anyone else with a 2019 Model S, or even other years, encountered similar symptoms? I'm trying to figure out if this is a common issue or something more serious before I schedule a service appointment. Any advice or shared experiences would be greatly appreciated!

✓ Accepted solution

ClearTheCode Admin

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

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ClearTheCode admin answer:

Experiencing reduced power and unusual noises from the drive unit in your Tesla Model S is a serious concern that warrants prompt attention. These symptoms often point to issues within the electric motor or its associated components.

  1. Identify the Problem:

    • Reduced Power: This indicates the motor or power electronics are not delivering optimal output.
    • Whining Noise: A whining sound, especially one that changes with speed or load, is a classic symptom of bearing wear within the drive unit, gear wear, or issues with the motor's stator or rotor.

  2. Possible Causes:

    • Drive Unit Bearing Failure: This is a relatively common issue in some older Tesla drive units, leading to noise and eventually reduced efficiency or failure.
    • Gear Wear/Damage: Internal gears within the reduction gearbox can wear down, causing noise and affecting power transfer.
    • Motor Stator/Rotor Issues: Problems with the motor's windings or rotor components can lead to inefficient operation and noise.
    • Inverter/Power Electronics Malfunction: While less likely to cause a distinct whine, issues with the inverter can lead to reduced power output.
    • Low Drive Unit Fluid: Although less common for sudden onset, insufficient or degraded drive unit fluid can exacerbate wear and noise.

  3. Diagnostic Steps (What a Shop Will Do):

    • Scan for Diagnostic Trouble Codes (DTCs): Tesla's diagnostic system will likely log specific codes related to drive unit performance or component health. Look for codes like DU_w027 (Drive Unit Warning), DU_w028 (Drive Unit Fault), or other motor-related error codes.
    • Listen with Stethoscope: Technicians will pinpoint the exact source of the noise.
    • Inspect Drive Unit Fluid: Check for proper level and contamination.
    • Motor Health Check: Advanced diagnostics can assess motor winding integrity and rotor health.

  4. When to See a Shop:

    • Immediately. Do not delay scheduling service. Continued driving with a failing drive unit can lead to more extensive and costly damage, or even complete failure, which could leave you stranded.
    • If any warning lights appear: Even if no lights are on now, if they illuminate, it's a critical sign.
    • If the noise worsens or power loss becomes more severe: This indicates rapid degradation.
    • Safety Concern: A compromised drivetrain can affect vehicle control and safety.

Contact Tesla service as soon as possible and provide them with a detailed description of the symptoms, including when the noise occurs and the nature of the power reduction.

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