Codes P0431 and P0303, catalytic converter misfire and overheating question

IFYUSER

MEMBER
2003 VOLKSWAGEN PASSAT
2.8L
V6
4WD
AUTOMATIC
186,000 MILES

I have a misfire on the left side bank 1 cylinder 3. I wanted to know if a bad catalytic converter from bank 2 from the right side would cause the misfire? Also I noticed the car has been overheating on hot days.

Thursday, September 9th, 2021 AT 11:58 PM

3 Replies

SQM

MECHANIC
6,383 POSTS

Hello,

There are few reasons you could have the misfire. Bad catalytic converter is one of the reasons that it can misfire. Then again it could be due to other factors.

I have attached the complete diagnostics for bot code P0431 and P0303.
Go through that step by step process, it will help you narrow down exactly the issue that you might have.

As for overheating, does it go all the way to red or runs hotter than usual?

https://www.2carpros.com/articles/symptoms-of-an-overheating-engine

Let me know of any questions.
Thank you.

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Friday, September 10th, 2021 AT 10:17 AM

IFYUSER

MEMBER
54 POSTS

It goes a fourth close to the red but not to the red then back down but I haven't driven it to a long time to tell ever since.

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Friday, September 10th, 2021 AT 12:59 PM

SQM

MECHANIC
6,383 POSTS

An engine could overheat for several reasons. You could have a faulty radiator fan or may be the water pump is bad and not circulating the coolant properly. Maybe a restriction in the cooling system. Or a stuck thermostat.
Check out this article, it goes over the typical overheating reasons and what to do:

https://www.2carpros.com/articles/engine-overheating-or-running-hot

Let me know if you have any questions or concerns.

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Friday, September 10th, 2021 AT 1:15 PM