Check light turn on, code p303

Tiny
JARROD ROOKS
  • MEMBER
  • 2007 KIA RIO
  • 205,000 MILES
My check engine light came on the code was p303 I changed the #3 coil pack and no luck. Then I noticed that I needed a flex pipe because it had a hole in it and got really loud one day after I replaced the pipe. The car ran a little better so I went for a ride to see if that would reset the light, but on the way back, I started to lose pressure and power and eventually the car stalled. Now I have to jump-start it and it runs really rough it's kind of loud and I'm not sure if it's bad coils, bad manifold, or damaged motor.
Sunday, November 28th, 2021 AT 12:19 PM

5 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,127 POSTS
Hi,

If you need to jump-start it, the first thing to do is this. Jumpstart the vehicle. Then, using a multimeter or voltmeter, check the alternator output. If the battery is weak due to not charging, it will cause all kinds of issues. If the alternator checks good, then we will need to charge the battery and have it load tested.

One last thought. Make sure battery terminals are clean, tight, and free of corrosion.

Here is a link with checking alt output. The link explains step by step.

https://www.2carpros.com/articles/how-to-check-a-car-alternator

Let me know what you find and if I can help.

Take care,

Joe
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Sunday, November 28th, 2021 AT 10:41 PM
Tiny
JARROD ROOKS
  • MEMBER
  • 2 POSTS
I know the alternate is good it will start right up and stay running I think the lack of power is draining the battery but I'm more concerned with the exhaust system.
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Monday, November 29th, 2021 AT 3:36 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,127 POSTS
Hi,

The engine power loss isn't draining the battery. The two are not tied together. However, the exhaust could cause power loss if there is a plugged catalytic converter. That could also cause a misfire. Take a look through this link and see if it mirrors what you experience.

https://www.2carpros.com/articles/bad-catalytic-converter-symptoms

If possible, record it running and upload it so I can hear what it's doing.

Let me know.

Joe
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Monday, November 29th, 2021 AT 5:22 PM
Tiny
JARROD ROOKS
  • MEMBER
  • 2 POSTS
Hey, thanks for helping me out, I will try that tomorrow, and send a video, but just to put this out there; when I changed the front exhaust pipe there was some rock sort of substance in the old pipe, and muffler or that maybe the catalytic converter I cleared all of it out, but is that a bad signal?
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Monday, November 29th, 2021 AT 6:16 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,127 POSTS
Hi,

Chances are the internal portion of the converter has come apart, and that's what you saw. See pic 1 below showing the insides of a converter, and see if it looks anything like what you saw. Also, here is a video that you may find helpful:

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

Let me know what I can do to help.

Take care,

Joe

See pic below.
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Monday, November 29th, 2021 AT 9:11 PM

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