Question

need  some help  i have  a  ware is the  efi  on a chevy cavalier  the  code is po303   i checked the spark plugs  any more ideas

Answer 1

Hi there, 

This code points towards a misfire on cylinder 3. Though you have changed the spark plugs, there are a few other possibilities causing the issue. Here is a list for you. 

P0303 CHEVROLET - Cylinder 3 Misfire Detected

Read more: https://www.autocodes.com/p0303_chevrolet.html