Qualifying Defects Under Illinois Lemon Law
What kinds of vehicle defects qualify for an Illinois Lemon Law refund — the substantial-impairment test under 815 ILCS 380 and common defect categories.
A defect qualifies under the Illinois Lemon Law when it substantially impairs the use or market value of the vehicle. The phrase comes from 815 ILCS 380/2(f).
Topics in this section
- Transmission defects
- Engine defects
- Brake-system defects
- Electrical and software defects
- Steering and suspension defects
- Infotainment defects
- EV-specific defects
The substantial-impairment test in Illinois
815 ILCS 380/2(f) defines a “nonconformity” as a defect that “substantially impairs the use or market value” of the vehicle. The test mirrors the standards used in other states. Use and market value — Illinois’s standard is slightly narrower than safety-prong states like California and New York, but Illinois courts apply it flexibly.
What’s substantial vs. trivial
Same examples that apply in other states:
- Transmission that shifts hard — qualifies.
- Engine that stalls — qualifies.
- Brake-pedal feel that varies — qualifies (safety implication affecting use).
- Power-window switch that intermittently fails — typically doesn’t qualify alone.
What’s NOT a qualifying defect
- Damage from accidents.
- Damage from unauthorized modifications.
- Normal wear.
- Neglect or misuse.
- Cosmetic flaws without functional impact.
How qualifying defects interact with repair-attempt counts
A qualifying defect alone isn’t enough — the consumer still needs to meet § 380/3 thresholds: four attempts or 30 cumulative business days out of service within the tight 12-month / 12,000-mile statutory warranty period (and any suit must be commenced within 18 months of delivery).
What court / arbitration considers
- Clean documentation.
- Consistent symptoms across multiple visits.
- Evidence the defect persists.
- Properly served § 380/3 notice.
- Defect aligns with documented manufacturer TSBs.
Related
Illinois Lemon Law — Frequently Asked Questions
Quick answers to the most-asked questions about Illinois's Lemon Law and ICFA.
Read → TopicIllinois Lemon Law Cases by Manufacturer
How the Illinois Lemon Law and ICFA apply to specific manufacturers — characteristic defect patterns, TSB histories, and settlement dynamics.
Read → TopicThe Illinois Lemon Law Process
Step-by-step: how an Illinois lemon-law case moves from repair attempts through manufacturer notice, BBB Auto Line arbitration (optional), court action, and settlement.
Read → TopicIllinois Lemon Law Remedies
What you can recover under Illinois's lemon-law framework — refund, replacement, cash-and-keep settlements, ICFA treble damages, and ICFA attorney-fee recovery.
Read → TopicThe Law: Illinois Lemon Law and ICFA
The statutes behind an Illinois lemon-law claim — the New Vehicle Buyer Protection Act (815 ILCS 380), the Illinois Consumer Fraud Act (815 ILCS 505), Magnuson-Moss, and timing rules.
Read → TopicVehicle Types Covered by Illinois Lemon Law
How Illinois's Lemon Law applies to used cars, leases, EVs, motorcycles, RVs, and commercial vehicles.
Read →Think you've got a lemon?
Compare your situation to your state's requirements — and connect with a vetted lemon-law attorney for a free case review.