The magazinenot to buy the SUV because handling problems could cause the vehicle to roll over on sharp turns.
As a result, Toyota said it had asked dealers to.
Government safety officials are also investigating.
Earlier this year, Toyota had come under fire by the federal government for not responding quickly enough with recalls to address faulty gas pedals on some of its other vehicles.
Toyota says it hopes to determine the cause of any problems with the GX 460 as soon as possible, but a spokesman says he's not sure how long that will take. He also says he's not clear if a recall will be issued.
The spokesman says engineers want to correct the problem so Consumer Reports can re-test the SUV and give it a satisfactory rating.
A Lexus official says the company will provide a loaner car for any customer who bought a 2010 GX 460 and is concerned about driving it.
Customers who have questions or concerns about the GX 460 can call Lexus at 800-255-3987.
The carmaker issued the temporary "stop sale" within hours after the popular consumer magazine raised the handling problem. It reflects Toyota's attempt to respond more quickly to safety concerns after being castigated by the federal government for dragging its feet on recalls to address faulty gas pedals.
Toyotaand has until April 19 to decide whether to contest the penalty following the recall of more than 8 million cars and trucks worldwide over gas pedals that are too slow to retract or can become stuck under floor mats.
The GX 460 is not covered by the pedal recalls.
Toyota hopes to determine the cause as soon as possible, but spokesman Joe Tetherow said Wednesday he is not sure how long that will take.
"They understand that time is of the essence to get this resolved quickly but correctly," he said. He was not sure if a recall would be issued, but said engineers are working to correct the problem so Consumer Reports can retest the GX 460 and give it a satisfactory rating.
More on Toyota's Troubles
Toyota to Temporarily Halt Sales of Lexus GX460
Consumer Reports Calls Lexus GX460 Unsafe
AP: Toyota Master of Legal Evasion, Deception
Another Civil Penalty Coming for Toyota?
Toyota Executive: "We Need to Come Clean"
Toyota Warned Europe of Pedals Weeks Before U.S.
Consumer Reports is closely read by many car buyers before choosing a new car or truck and has raised red flags over Toyotas previously. In January, the magazine pulled its "recommended" rating on eight vehicles recalled by the automaker due to faulty gas pedals.
In this case, Consumer Reports said the Lexus problem occurred during tests on its track. In a standard test, the driver approached a turn unusually fast, then released the accelerator pedal to simulate the response of an alarmed driver. This caused the rear of the vehicle to slide outward.
Under normal circumstances, the electronic stability control should quickly correct the loss of control and keep the SUV on its intended path. But with the GX 460, the stability control took too long to adjust, which could cause a rollover accident if one of the sliding wheels were to strike the curb or another obstacle, said Gabriel Shenhar, Consumer Reports' senior auto test engineer, one of four testers who experienced the problem.
The magazine said it is not aware of any reports of the GX 460 rolling over. It tested two separate vehicles, both of which experienced the problem, but neither rolled over.
Julia Piscitelli, a National Highway Traffic Safety Administration spokeswoman, said in a statement the agency was testing the GX 460 to ensure it complies with federal safety standards on electronic stability control and to understand how Consumer Reports reached its conclusions.
"It is our belief that ESC should prevent the kind of fishtail event described in CU's tests," Piscitelli said.
The warning label on the model will remain until Toyota addresses the handling issue with the seven-seat SUV.
Tetherow said Toyota is looking at the GX 460's stability control software, among other possible causes.
Templin said in a statement he was "confident that the GX meets our high safety standards" and said Toyota's engineering teams were testing the GX using Consumer Reports' specific parameters.
The GX 460, which starts at about $52,000, is built on the same platform as the Toyota 4Runner. However, Consumer Reports said the problem did not occur during similar tests on the 4Runner. According to Toyota's Web site, both vehicles are about 6 feet tall, but the GX 460 is about 3 inches taller.
Consumer Reports said the last vehicle to receive such a safety warning was the 2001 Mitsubishi Montero Limited, a large SUV. In that case, testers said the wheels lifted off the road during standard avoidance-maneuver tests, which also posed a rollover risk.