P0421code

[Mrfixit24]

Got my car scanned by Autozone and gave code p0421 my 03 galant has 2 converters and one is built into the manifold and trying to find out which one is bad

Topic

[Mike]

Bank 1 cat is usually the one at the front of the motor on transverse engines. I would test the 02 sensor downstream of that cat before you have a new cat put on first.

[Mrfixit24]

Ok how would I go by testing the o2 sensor

[NissanMaxx]

You can test the o2 sensors by using a live scanner. The primary o2 sensors should switch rapidly while the secondary o2 sensors should steady at .45. The o2 sensor that you are checking I think is a secondary o2 sensor so it should steady at .45.

[dreamer2355]

http://www.obd-codes.com/p0421

You can also use a temp gun and measure the temperature before and after the cat. There should be a 100f difference. Also a 5 gas analyzer would be another choice.

Id also be doing a visual inspection of the exhaust.

I also saw this from a quick Google search –

http://www.thegalantcenter.org/showthread.php?44237-Code-P0421

[Mrfixit24]

Thanks will post a reply

[Mrfixit24]

What should I look for when doing a visual inspection of the exhaust

[college man]

here is a video to help you check your exhaust.

[Mrfixit24]

Yea i would like to check for that and check the sensors before I replace the manifold which is very expensive

[EricTheCarGuy]

I’ve never tried this but I’d love to know if it works.

[Author]

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