Why does my 2014–2022 Mitsubishi Mirage whine when I accelerate?

Short answer: A whine on the Mirage can come from the CVT (the belt-and-pulley automatic) or from the engine's accessory belt. Owners often find a squeal at takeoff is just the accessory belt. A transmission whine with slipping, shudder or dark fluid is the one to worry about.

Symptom: A whine or squeal that rises as you press the gas, sometimes only at takeoff, sometimes at all speeds.

What to check first

1. Check the accessory (serpentine) belt for glazing, cracks and tension. A squeal at takeoff is often the belt.
2. Notice if the noise changes with engine speed or road speed. Engine speed points to belts and accessories; road speed points to the CVT or bearings.
3. Have the CVT fluid checked for level and condition. Mitsubishi calls for its own CVT fluid.
4. Make sure the parking brake isn't dragging. An r/MitsubishiMirage owner was told hard launches and driving with the parking brake on can stress the CVT.

Likely causes

1. Worn or loose accessory belt. A common, cheap cause of a squeal on takeoff.
2. Low or worn CVT fluid. Can cause whine and poor engagement.
3. Worn CVT belt or pulleys. Mitsubishi's service procedure has techs inspect the CVT belt and replace the transmission if the belt is worn or damaged.

What it usually costs

A belt is a small repair. I couldn't find a reliable Mirage-specific price for CVT replacement, so if a shop says the transmission is the problem, get the diagnosis in writing and a second opinion.

Is it safe to keep driving?

A belt squeal is OK to drive on briefly but get it fixed, since the belt runs the alternator. A CVT that whines and also slips, shudders or loses power should be checked before highway driving.

DIY or shop?

Checking and replacing the accessory belt is DIY for many owners. CVT diagnosis is shop work.

Recalls, bulletins and complaints in plain words

• No recall covers Mirage CVT whine in NHTSA's records.
• NHTSA complaints: only 6 of 132 Mirage complaints from 2014–2022 mention the CVT, transmission or whine. Owners mostly ask about it on forums instead.

What owners report

• A Mirage G4 owner on r/MitsubishiMirage with a squeal was pointed at the accessory belt first.
• In another r/MitsubishiMirage thread, an owner asked about a whine that gets louder with the gas, and replies split between normal CVT noise and something to check.
• A r/MitsubishiMirage "transmission question" thread warned against hard launches and driving with the parking brake on.

My take

My advice as a former lot tech: before anyone tells you the transmission is bad, have them take the accessory belt off for a few seconds and start the engine. If the noise is gone, you just saved yourself a lot of money.

Vehicle focus: 2014–2022 Mitsubishi Mirage and Mirage G4 with the CVT automatic.

Safety / mechanic note

If the car slips or loses power, don't take it on the highway until it's checked. Verify with a mechanic.