97 sl2 obd codes- p0300 and p0420 help please?

halo006 · 04-05-2008, 04:34 PM

I have a 97 saturn sl2 that ran perfectly fine two days ago and now runs like total crap, service engine light came on and next thing u now my car is sturttering in high gear unless i gun it. at idle it sounds fine.. and the stuttering/hesitation problems dont start till the engine is warmed up.. Had my obd scanned and it read the following codes : p0300 multiple/random misfire & p0420 catalyc efficiency below thresh hold .. how can i fix this problem with out going out and spending all my money on uneeded parts? any help would be appreciated.. Thanks

RC1488 · 04-05-2008, 09:24 PM

Change your Engine Coolant Temperature Sensor first. This sensor can crack and send false data to the PCM. It helps adjust fuel mixtures, idle rpms, and whether or not the systems goes into closed loop fuel delivery. New ones are brass and last the lifetime of the car. Change that ASAP