Hey I'm getting these 2 codes in my audi A4 PO431,PO421,So do i hve to chage my O2 sensor or catalytic civerter, Plzzz help me !!!

5

Asked by Feb 07, 2015 at 10:58 PM about the 2003 Audi A4 3.0 Quattro

Question type: Maintenance & Repair

I'm keep getting these PO431,PO421
in my Audi,i gust last owner hve used
low octain gas that's y catalytic
civerter getting hot, So wht i hve to
do ?? :(

5 Answers

9,905

your car has a missfire. most likely a bad spark plug or coil pack. im guessing you have not much knowledge about cars so take it to a VW/Audi certified mechanic ONLY> never take your audi to the average joe blow mechanic unless you want more issues and many repair bills. Have them check your car for a misfire if you have not had a tune up done in a long while i would suggest having them do one. which usually includes new plugs and an oil change. and if your ussing low octane fuel in your audi your not supposed to You have to use only the best octane gas you can find since low octane gas will wreck havoc with your audis engine and emissions systems such as the catyletic converter.

5

So is there nothing wrong with o2 Sensor ?????

9,905

that would be a most likely no probly not but if the car persists after the tune up then start looking at a new cat. a new cat will run you up any where from 500-1500 $ depending on wher eyou buy it since they come as a full set built unit and should come with a o2 sensor if im correct.

15

I have an Audi A4 Quattro 3.0 2003 I went to the market last night and when I got back in car it wouldn't start. The dash lights went on, but no noise when turned the key. I was about out or out of gas. I thought it might be that. Got gas and put in car, still no start or noise. Today it's starting fine. Shows error code P0421 Any clues as to what is most likely wrong? Thanks so much!!

1 of 1 people found this helpful.
9,905

Sent a reply in private message be sure to check it and for separate issues you should open a separate tab. i follow all audi and vw questions so i should see the question within a days time thanks.

1 of 1 people found this helpful.

Your Answer

Add photo

Related Questions

A4

Looking for a Used A4 in your area?

CarGurus has 10,525 nationwide A4 listings starting at $1,000.

ZIP:

Search Audi A4 Questions

Audi A4 Experts

#1 Deathjam4
Deathjam4
Reputation 3,440
#2 lukeyramone
lukeyramone
Reputation 540
#3 Tom Demyan
Tom Demyan
Reputation 450
View All

Related Models For Sale

Used BMW 3 Series
1,001 Great Deals out of 31,467 listings starting at $1,000
Used Audi A6
139 Great Deals out of 6,105 listings starting at $2,488
Used Mercedes-Benz C-Class
643 Great Deals out of 24,832 listings starting at $1,995
Used Audi A3
91 Great Deals out of 5,140 listings starting at $3,995
Used Audi S4
58 Great Deals out of 1,732 listings starting at $4,650
Used BMW 5 Series
493 Great Deals out of 16,476 listings starting at $2,000
Used Honda Accord
1,054 Great Deals out of 66,814 listings starting at $1,000
Used Ford Mustang
689 Great Deals out of 44,321 listings starting at $1,500
Used Audi A8
62 Great Deals out of 2,085 listings starting at $2,999
Used Mercedes-Benz E-Class
423 Great Deals out of 19,866 listings starting at $1,200
Used Honda Civic
844 Great Deals out of 83,686 listings starting at $1,200
Used Chevrolet Camaro
373 Great Deals out of 31,271 listings starting at $2,500

Used Cars For Sale

2018 Audi A4 For Sale
774 listings starting at $40,691
2017 Audi A4 For Sale
46 Great Deals out of 3,608 listings starting at $26,990
2016 Audi A4 For Sale
16 Great Deals out of 219 listings starting at $22,591
2015 Audi A4 For Sale
24 Great Deals out of 430 listings starting at $16,900
2014 Audi A4 For Sale
52 Great Deals out of 1,296 listings starting at $12,995

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.