Tuesday, June 18th, 2019 AT 2:06 PM
I recently had a p0421 and a p0300 code pop up. I got both oxygen sensors and the catalytic converter replaced about a week ago. The p0421 code is gone but the p0300 code came back along with the car having a rough idle, shaking when driven, and losing power to the point that the car will not go over 40 mph. The spark plugs, coil packs, spark plug wires and PCV valve have all been replaced and the timing belt and battery are under a year old. Fuel injector cleaner was run through the car just in case it was a clogged injector. I also noticed the PCV hose was cracked so that will be replaced shortly(though I don't think this is what is causing the code. Are there any other reasons the car would be giving me this code?