Illinois lemon law statute of limitations (2026)

The plain-English guide to Illinois lemon law time limits — the 18-month suit deadline and the 1-year / 12,000-mile presumption period, built from the Illinois Attorney General's auto-sales publications and the New Vehicle Buyer Protection Act (815 ILCS 380/), not law-firm marketing. Last reviewed: October 2026. For the full filing walkthrough, see our Illinois lemon law filing guide.

Two clocks, not one

Illinois lemon law has two different time limits, measured from the same delivery date but doing different jobs. The statutory warranty period — 1 year or 12,000 miles from delivery — is when the repair attempts and days out of service must occur for the presumption to apply. The 18-month suit deadline is the court limitations period for commencing suit. The longer suit period does not extend the shorter presumption window.

Our Illinois lemon law filing guide states the 18-month suit rule below and no other general limitations period, so this page does not add one. Deadlines are the highest-stakes facts in a lemon law case — verify yours against the primary sources before you rely on any date, including ours.

Work through them in this order. First, line your repair records up against the 1-year / 12,000-mile presumption period — that tells you whether the presumption is available on your facts. Then compute the 18-month suit date below, because a strong repair history does not help if the suit itself is late. If either answer is uncertain, resolve the suit date first: it is the one that cannot be revisited later. Keep the dates, repair-order numbers and reported problems together in the free repair log.

The presumption period: 1 year / 12,000 miles

The presumption arises when, within the statutory warranty period — 1 year or 12,000 miles from delivery, whichever first — either the same nonconformity was still there after 4 or more repair attempts, or the vehicle was out of service by reason of repair for a cumulative 30+ business days with the nonconformity still existing — and the manufacturer received prior direct written notification with an opportunity to correct (§3(h)). Different defects do not combine, and Illinois has no reduced-attempt safety shortcut: the same 4-times / 30-business-day thresholds apply to safety defects too. The test-by-test wording is in the tests section of our Illinois filing guide.

The Illinois Attorney General warns that many consumers lost their remedy by waiting longer than 12 months from purchase — treat the 1-year mark as an action deadline for the early steps, not just a window to watch.

The 18-month suit deadline

Under 815 ILCS 380/6, the suit clock runs 18 months from original delivery. It is extended by the days the matter was pending in the informal dispute procedure — so filing with the manufacturer's program early also protects your clock.

This is a court limitations period — the single most important date in your case. Use the Illinois lemon law deadline calculator to estimate yours, then verify it before you rely on it.

How to compute the 18-month date

Record the two clocks separately, each with its own evidence. For the suit date, find original delivery in the contract and delivery records and add 18 calendar months — that is the unadjusted estimate the calculator uses, because it does not collect the dates needed to apply a program-pendency extension. For the presumption, compare delivery plus one year with the 12,000-mile milestone and check when the repair attempts and business days out of service actually occurred, rather than assuming the longer suit period extends that window. If you used the manufacturer's informal dispute procedure, keep the confirmation of when the matter began and ended there and ask an attorney to confirm the number of pending days and the adjusted court date under §4(b) — ordinary dealer visits or manufacturer correspondence are not program-pendency days.

If the date appears missed

If the estimate has already passed, speak to a licensed Illinois attorney promptly, before purchasing a packet, because missing an applicable deadline may put the statutory remedy at risk and the calculator cannot decide whether an extension applies or another law provides an option. Bring the warranty, repair orders, notice proof, and program records so the dates can be evaluated together, and keep a copy of your inputs and calculation — missing information is not extra time.

Primary sources: 815 ILCS 380, §§3, 4 and 6 · Illinois AG auto guidance

Estimate your date with the Illinois lemon law deadline calculator, then verify it before relying on it.

A worked example (fictional dates)

Inputs: original delivery April 7, 2025; a claim under the manufacturer’s dispute program was pending for 45 days.

The arithmetic: 18 months after delivery is October 7, 2026. The statute extends the period by the days a claim was pending in the manufacturer’s program — 45 days here — which moves the estimate to November 21, 2026. The presumption window is separate and shorter: one year or 12,000 miles from delivery.

What the calculator doesn’t handle: it does not ask whether a program claim was pending or for how long, so it shows the unextended October date. If you used a manufacturer program, add the pending days yourself and confirm the count against the program’s records.

§3(h) notice, filing, and remedies — in the full guide

Three steps sit between the presumption and a remedy, and each is covered in our Illinois filing guide. First, the §3(h) notice: the manufacturer — not just the dealer — must receive prior direct written notification and an opportunity to correct; the statute does not require certified mail, but a trackable mailing is the practical way to prove you sent it, and our $29 packet includes a draft §3(h) notice letter. Second, filing: a qualifying manufacturer's informal dispute procedure comes first if one exists and you were told about it in writing, and circuit court after that — the Act sets no filing fee of its own (circuit-court clerk fees apply), and the Illinois lemon law has no attorney's-fee provision, so it does not shift your legal fees to the manufacturer. Third, the guide explains what happens after you file and the remedies — repurchase or replacement. None of these steps extends the 18-month suit deadline above, and the AG warns that waiting longer than 12 months from purchase has cost consumers their remedy, so do the early steps early.

When to talk to a lawyer instead

Some cases are not straightforward DIY cases — in particular where the defect is a serious safety hazard, the manufacturer has denied or disputes the claim, or your 18-month deadline has passed or is under 30 days away. The lawyer section of our Illinois filing guide lists the situations in full. Because Illinois' lemon law has no fee-shifting, ask any attorney how they charge before you hire them.

Sources: Justia — 815 ILCS 380/ (statute reprint) · IL AG — Auto Sales and Repairs