2002 Toyota Camry 2002 Camry Fault Code P0421

TOPHERBRO

MEMBER
2002 TOYOTA CAMRY
4 CYL
FWD
AUTOMATIC
172,000 MILES

Hey guys. Love the site. I have a 2002 Toyota Camry 4cyl. LE with a check engine light on most of the time. I was able to retain a fault code of P0421. I am pretty sure that the problem is an oxygen sensor, but I am not sure. I have gone months with it blinking on and off. I am getting less gas mileage, but the car seems to run well. It recently started lagging when I press the accelerator after starting. Is the oxygen sensor the likely culprit, and, if so, how difficult is it to buy the part and replace it myself? Thanks.

1 Reply

BLUELIGHTNIN6

MECHANIC
16,542 POSTS

Hello
Thanks for the compliment.

P0421 Warm Up Catalyst Efficiency Below Threshold (Bank 1)

The trouble code means that the oxygen sensor is reading that your catalytic converter is no longer operating properly. Either the oxygen sensor(s) is faulty and is giving an incorrect reading or the catalytic converter is faulty. You should have a flow test performed on the cataytic converter to ensure it is performing properly. You can also check your oxygen sensor(s) before replacing them. To learn how to check your oxygen sensor(s), just follow the link below..

https://www.2carpros.com/how_to/how_to_test_oxygen_sensor.htm

If your oxygen sensor(s) is at fault then they are very simple to replace. Simply unscrew and remove. If the converter is clogged or faulty then this, however, will have to be repaired at a muffler shop.

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