Symptoms
- High-pitched whine that changes with speed
- Whine worse under acceleration
- Noise fades at steady cruising speed
- Vibration accompanying the whine
Likely causes
- CommonLow or old CVT fluidCVT fluid is specialized and lubricates the pulleys and belt; degraded fluid increases friction noise.
- CommonWorn pulley bearingsBearings that support the variable pulleys wear over time and whine under load.
- PossibleStretched or worn drive belt/chainThe metal belt or chain that transmits power can wear and generate noise.
- PossibleLow fluid causing pulley slipInsufficient clamping force lets the belt slip slightly, creating whine.
- Less commonFailing torque converter (on CVTs that use one)Some CVTs use a torque converter that can whine as it wears.
What to do
- Check the CVT fluid level and condition using the manufacturer's specific procedure, since CVT fluid checks often differ from conventional automatics.
- Note exactly when the whine occurs: accelerating, cruising, or only at certain speeds.
- Avoid using non-CVT-specific fluid, since the wrong fluid can cause belt slip and damage.
- If fluid is low or overdue, have it serviced with manufacturer-approved CVT fluid only.
- Avoid towing or hard acceleration until it's checked, since CVTs are more sensitive to stress than conventional automatics.
- Have a dealer or CVT-experienced shop scan for transmission codes and check pulley condition if the noise continues.
- Don't delay diagnosis, since CVT belt or pulley failure can leave the car undrivable.
Tools and parts
- CVT-specific dipstick or checking procedure
- Flashlight
Transmission fluid (correct type for vehicle)Search: “transmission fluid type for [make model year]”
When to call a pro
See a shop experienced with CVTs, ideally a dealer, since CVT internals are specialized and the wrong repair approach can cause more damage.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.