2003 Pontiac Bonneville p300 p420

2003 PONTIAC BONNEVILLE
V6 • FWD • AUTOMATIC
Avatar
KNISALAD
  • MEMBER
  • 1 POST
I've had this problem for over a year now. sometimes car idle smoothly, others it chugs hard, almost stalls itself out/ battery fluctuates. When accelerating easy it runs normal. when accelerating heavy there is a loud chirping/ squeeking noise, then the engine shakes violently, and has very little power. Replaces MAF sensor/ air filter one year ago. Spark plugs/ fuel filter 2 years ago.
Apr 18, 2015 at 9:27 AM
Advertisement
Avatar
HMAC300
  • ✓ASE Certified Mechanic
  • 48,601 POSTS
  • ASE Certified Mechanic
code 300 is a misfire and a pro should diagnose this as it can lead to buying a lot of parts that are not needed. code 420 is a converter code which means if it's not a bad O2 sensor or air leak prior to converter you need a new one which you didn't post mileage so I suspect it's a lot on the car.
Apr 18, 2015 at 10:32 AM
Join 2CarPros for free, one of the most advanced car repair communities on the internet. From first-time drivers to seasoned mechanics, everyone is welcome to reply, share details, and get better answers. You can add a temporary image or video first; uploads are limited to 20 MB.
Ask a Free Question
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.