The check engine light comes on my 2000 RX300, when I drive locals and goes away when I drive on highway. Autozone told me the error code was P1150 or so.

Anyone has suggestions?

Thanks.

P1150 Air/Fuel Ratio Sensor Circuit Range/Performance Malfunction (Bank 2 Sensor 1)--the easy one to replace. It's the one below the exhaust manifold on the radiator side of the engine. Look at the attached document (below) starting on page SF 75 for troubleshooting info. The part number is 89467-48011, I think. Search this forum by that number to be sure it is correct. $125-175 for the part, depending on where you buy. Popular opinion is to buy OEM--search the correct OEM part number on eBay. Keep in mind, this is not an O2 sensor even though they may look the same.

Another fault may be that the fuel cap is not sealing properly. I saw on another post where a member wrapped several layers of teflon tape under the "O" ring seal of the cap to create a tighter fit. Good luck.