P0420 CEL Code

[hondakpro]

Has anyone seen an aftermarket air intake causing the P0420 cel?
I put a new cat and o2 sensor on, it was good for a while and now its been coming on and off. I've had a couple people say my car has been smelling like gas. I've been wondering if the intake is messing with the A/F ratio. Please let me know if anyone has seen this before.
Thanks!

 

[XpL0d3r]

It's possible that if your system was running super rich you may have killed an o2 sensor. In converse, a bad o2 sensor can cause your engine to run rich as well.

If your air filter is dirty or clogged, it can cause your system to run rich. Also any leaks from the manifold can cause this too.

If that's the only code you're getting, check your secondary o2 sensor. If you have one that is, since you didn't read the rules and post your make and model Guessing that since you posted in the 7th gen section that you do, though.

Also check the wiring for the sensor, because I had part of my sensor wire melt as it was slightly too long and rested on the exhaust.

A whole website based on this CEL
http://www.p0420.com/

 

[hondakpro]

I haven't been on this forum in a while, I'm pretty sure I used to have a different username. Its a 2003 civic ex. The CEL has been going off every few days then coming back on. Do you think the o2 sensor is still good? I'm pretty sure the air filter is some what dirty I'm going to put stock back on and I'll examine the o2 sensor / wires. Thanks for the reply!!

 

[XpL0d3r]

A dirty air filter really will just give you shitty gas mileage, unless it's so dirty that it's actually clogged and starving the system of air.

A bad o2 sensor can cause the CEL as well as a gas smell as it can mess with the proper A/F ratio. Borrow a sensor from a buddy or something if you can and throw it in there to test it out.

 

[lowlife9]

an intake wouldn't cause you to run rich unless you didn't reset the ECU. a cheap 02 sensor would what brand 02 sensor did you use ???