Qualifying Defects: What Counts as a Lemon in Missouri

Missouri’s Lemon Law (§ 407.567) covers any “nonconformity” — a defect or condition that substantially impairs the use, market value, or safety of the vehicle and is not the result of consumer abuse.

The “substantially impair” test

Under § 407.567, a “nonconformity” must:

1. Substantially impair the use, market value, or safety of the vehicle.
2. Persist after a reasonable number of repair attempts (4 attempts or 30 working days OOS).
3. Be covered under the express manufacturer warranty at the time of the first report.
4. Not be caused by consumer abuse, alteration, or unauthorized modification.

The seven defect categories most often qualifying

1. Transmission — Hard shifts, slipping, fluid leaks, total failure.
2. Engine — Stalling, misfires, excessive oil consumption, knocking, failure.
3. Brakes — Pulsation, dragging, ABS failure, soft pedal, premature wear.
4. Electrical — Battery drain, electrical-system warning lights, module failures.
5. Steering & suspension — Pulling, drift, EPS failure, shock failure, alignment failure.
6. Infotainment — Head unit lockup, Bluetooth/CarPlay failure, backup camera failure.
7. EV-specific — Battery degradation, charging failures, regen brake failures.

What does NOT typically qualify

• Cosmetic — paint, trim, leather (unless safety-related).
• Tires, batteries, wear items — not covered under express warranty.
• Modifications by consumer or unauthorized installers.
• Damage from accidents or environmental (hail, flood, tornado).
• Issues outside the 1-year Rights Period.

Missouri climate / geography factors

• Tornado Alley exposure — hail damage common; documentation must distinguish defect from weather.
• Hot humid summers — HVAC stress, condenser corrosion, electrical-connector failures.
• Cold winters with ice storms — battery, ignition, fluid viscosity, brake/tire issues.
• Ozark mountain driving (southern MO) — brake and transmission stress.
• Flat plains highway driving (I-70, I-44, I-29) — sustained high-load running.
• Karst topography / cave country — minor flooding exposure in some regions.

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