2002 Hyundai Elantra Q&A

2002 Hyundai Elantra Question: i have a hyundai matrix car

I did the system checkup last week and it shows 4 misfires. like cylinder misfire -
Answer 1
could be plugs or other issues. seek proper diag and est -
Comment 1
thanks. these are the misfire codes: 0121, 0300, 0301, 0303 -