My name is ***** ***** I am a licenced diagnostic technician with over 20 years experience.
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Ill go through these three codes.
p0201 - Injector control circuit cylinder 1.
p0300 - multiple misfire detected
p0449 - Evaporative Emission (EVAP) Vent Solenoid Control Circuit
the p0221 and p300 are probably related with each other. You could have a injector problem, or the wiring to the injector needs to be checked. When the injector doesnt fire properly, the computer notices this and stores this code, than of course the misfire code from that injector proplem.
THAt injector needs to be checked as well as the wiring to the pcm. I would also recommend a tune up (spark plugs, boots or wires and filters).
The other code (p0449), is one of the most common GM trouble codes out there next to the misfire one. It is a emissions code.
It is for the cannister vent solenoid, That is located under the vehicle close to the gas tank and charcoal cannister,
It is a 2 wire solenoid that vents and closes the fuel vapours in the system. You can activate it with a scan tool or jumping it direcly and seeing if it holds pressure with a smoke machine. but, It is a very weak valve that has a high failure rate. so 99 % its the valve thats failing.
I hope i have ansered your question and will always gladley answer follow up questions