Three standard warning lights came on..4WD, check engine, and slip. Threw a PO138 code. Local mechanic replaced this O2 sensor. Lights back on after 30 miles driving. Codes cleared with battery unhook and diagnostic computer. Code still reads. Lights back on. No other codes shown. 2011 RAV4 sport 4 cylinder Mechanic wants to replace another O2 sensor not showing on diagnostic. ???