1997 Other Plymouth Models 4 cyl Two Wheel Drive Automatic 193, 80 miles
Car runs great, and gets about 26 MPG on the road. There is no hesitation and runs smooth. SL came on in December, mechanic said misfire code, replaced plugs and plug wires. SL came on again in January, mechanic said misfire code, replaced PCV Valve and hose. SL came on again late January. OBD11 codes were p0420, p0300, p0301, p0303, and p0304. Failed Ca Smog test due to HC being over the max when tested at 25 MPH. (Max 49 - result 56). Erased codes and have put on 150 miles since then and OBD11 scan says PASS on everything, and NO CODES.
How do I bring the HC readings down? And what could be other reasons it was higher on the 25 MPH test but passed the 15 MPH test?
The code p0420 says the catalyst efficiency is below threshhold. Does that mean that the catalytic converter needs to be replaced?
Any help would be deeply appreciated.
Monday, February 4th, 2008 AT 12:51 PM