Pull the negative battery cable for a few minutes and it will reset, clearing the codes. (10mm)
I grabbed this el-cheapo special off Amazon $25 and it's a great addition to the `Yota tool box.
MOTOPOWER MP69033 Car OBD2 Scanner Code Reader Engine Fault Code Reader Scanner CAN Diagnostic Scan Tool for All OBD II Protocol Cars Since 1996, Yellow
Amazon.com
Good luck!