(CBS) — A decade after the problem was discovered, there are still plenty of defective Illinois license plates on the road, reports WBBM Newsradio’s Nancy Harty.

Chances are you’ve seen one – a plate that is peeling, rusting and difficult to read.

The Illinois Secretary of State’s office identified the manufacturer’s problem with the reflective coating in January of 2004.

Since then, spokeswoman Beth Kaufman says the office has replaced half a million plates – ones that were issued between 2001 and 2003.

Canada, New York and California have also had similar problems and traced the issue back to the reflective coating made by 3M.

Kaufman says the plates are covered under a warranty, so replacements don’t cost drivers or the state any money.

It’s not clear how many defective plates are still out there – the Secretary of State’s office wasn’t able to provide WBBM with a number.

A 2009 Tribune story says it was originally 1.1 million.

The police chief of Buffalo Grove says his officers often see such plates and remind drivers it’s their responsibility to replace them.

To report potentially defective plates, visit www.ilsos.gov/defectiveplate/defectiveplatecontact.jsp.