My IQ was tested some years ago as part of a diagnostic tool for Aspergers Syndrome. I scored 153. Lots of Aspies score very high but have poor social coping mechanisms. Even more score poorly, to the point of being borderline... in need of learning support in schools.
It's not known whether these low scores reflect the actual intelligence or if maybe the testee was just difficult to measure.
RE: Car Help
Mine did that for a while on account of a "miss-fire".The mechanic just put a cleaning solution into the fuel tank and said to drive as normal. The warning light hasn't come on since.