Error code P0421- wouldn't start, now is starting

15

Asked by Jul 19, 2015 at 07:47 PM about the 2003 Audi A4 3.0 Quattro

Question type: Maintenance & Repair

Audi A4 Quattro 3.0 virtually out of gas last night. drove to store fine. wouldn't start after
shopping. was raining, not sure that mattered. Put in gas last night, no start. Dash lights
went on, no noise when turn key. Today has been starting fine. clock had stopped and
now has started again. getting error code P0421. Likely causes/fixes? thanks so much!!

5 Answers

3,725

p0421- warm up catalytic converter, bank 1- efficiency below threshold, causes---catalytic converter, wiring, or H02S2 sensor

15

I know that's the error code but do you know with my other things that happened which is the most likely thing wrong and how Big a job it is to fix it? BTW it's been starting all day now and working fine so don't know what that means either Thank you so so much

3,725

could most likely be your wires, if it happens again while raining have it checked out.

Best Answer
15

Really appreciate!! You don't think it will happen before then? Or I need to get it checked out even if it's starting?

3,725

yes to check it out is always a good thing, but trust me to look for a fault that is not there is difficult.

Your Answer

Add photo

Related Questions

A4

Looking for a Used A4 in your area?

CarGurus has 10,684 nationwide A4 listings starting at $500.

ZIP:

Search Audi A4 Questions

Audi A4 Experts

#1 Deathjam4
Deathjam4
Reputation 3,550
#2 lukeyramone
lukeyramone
Reputation 540
#3 Tom Demyan
Tom Demyan
Reputation 460
View All

Related Models For Sale

Used BMW 3 Series
1,020 Great Deals out of 31,421 listings starting at $1,000
Used Audi A6
126 Great Deals out of 6,171 listings starting at $2,488
Used Audi S4
52 Great Deals out of 1,747 listings starting at $4,650
Used Audi A3
70 Great Deals out of 4,725 listings starting at $2,995
Used Mercedes-Benz C-Class
588 Great Deals out of 23,279 listings starting at $1,995
Used BMW 5 Series
481 Great Deals out of 16,591 listings starting at $2,000
Used Honda Accord
992 Great Deals out of 62,549 listings starting at $999
Used Ford Mustang
733 Great Deals out of 42,724 listings starting at $1,300
Used Audi A8
56 Great Deals out of 2,004 listings starting at $2,750
Used Chevrolet Camaro
418 Great Deals out of 31,646 listings starting at $2,395
Used Honda Civic
815 Great Deals out of 78,114 listings starting at $900
Used Mercedes-Benz E-Class
458 Great Deals out of 19,836 listings starting at $1,500

Used Cars For Sale

2018 Audi A4 For Sale
1,668 listings starting at $38,955
2017 Audi A4 For Sale
47 Great Deals out of 2,913 listings starting at $24,999
2016 Audi A4 For Sale
17 Great Deals out of 219 listings starting at $21,491
2015 Audi A4 For Sale
13 Great Deals out of 480 listings starting at $16,400
2014 Audi A4 For Sale
62 Great Deals out of 1,294 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.