Toyota and Lexus have just announced the recall of approximately 740,000 vehicles in the U.S. concerning a leaking master cylinder for the brake system.

Both Toyota and Lexus have announced a safety recall that will affect 1.66million vehicles worldwide, with 740,000 vehicles in the U.S., 600,000 in Japan, and the remaining 320,000 vehicles in other world markets such as Europe.

The recall will affect a total of six models in the U.S., two Toyota models and four Lexus models. The Toyota vehicles in the U.S. affected by the recall include 2005 and 2006 Avalon sedans, as well as 2004-2006 non-hybrid Highlander SUVs. Lexus will be recalling 2004-2006 RX330 SUVs, as well as the 2006 Lexus GS300, IS250 and IS350 vehicles in the U.S.

Toyota says that the issue stems from the use of non-Toyota branded brake fluid, which the automaker states contains special lubricating polymers that keep the master brake cylinder seal fresh. If customers or dealers were to replace the factory brake fluid with aftermarket fluid, the polymers will not be present to keep the seal fresh, causing it to potentially dry, curl and eventually leak from the master cylinder into the brake booster.

This leak should trigger the brake warning lamp in the gauge cluster, and if left untreated, stopping power can gradually decrease.

Toyota will begin contacting owners in the U.S. about the recall next month.