Looks like the catalytic converter may be shot on my wife's 2011 Honda Pilot.  Got the P420 code on the OBD2, which from my limited understanding denotes that the converter is showing to be functioning below standard efficiency and needs to be replaced or there could be a problem with 1 of the 2 O2 sensors but this is a less likely scenario.

Any idea if this is a DIY repair or do I have to find a mechanic or bring it to the dealer?  Is there anything else I might be missing?

 

Thanks!

 

 

 

I think I fixed this on an Accord once by tricking the o2 sensor with a spark plug non-fouler.. was pretty simple and permanently fixed the CEL


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If all you care about is turning off the light, you can use a spark plug non fouler as mentioned above or they sell a specialized plug that backs out the o2 sensor enough so it doesn't trip the code.

6 years seems like an awfully short lifespan for a cat though. Unless you were running incredibly rich the whole time, I'm not convinced your cat is actually dead.


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If all you care about is turning off the light, you can use a spark plug non fouler as mentioned above or they sell a specialized plug that backs out the o2 sensor enough so it doesn't trip the code.

6 years seems like an awfully short lifespan for a cat though. Unless you were running incredibly rich the whole time, I'm not convinced your cat is actually dead.


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1 hour ago, mikeyjones said:

If all you care about is turning off the light, you can use a spark plug non fouler as mentioned above or they sell a specialized plug that backs out the o2 sensor enough so it doesn't trip the code.

6 years seems like an awfully short lifespan for a cat though. Unless you were running incredibly rich the whole time, I'm not convinced your cat is actually dead.


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If all you care about is turning off the light, you can use a spark plug non fouler as mentioned above or they sell a specialized plug that backs out the o2 sensor enough so it doesn't trip the code.

6 years seems like an awfully short lifespan for a cat though. Unless you were running incredibly rich the whole time, I'm not convinced your cat is actually dead.


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Thanks, mickey.  The car just hit 100K miles, and I don't know if it was running rich, I wouldn't think so since I haven't adjusted anything since we bought it new and my wife has taken it back to the dealer for several oil changes and they seemed to check everything, and of course recommend fixing it.

I would like to fix it correctly or at least diagnose it correctly and know for certain what the problem is.

 

Thanks again

 

 

 

Bad 02 sensor.

I did the capacitor/resistor rig, worked on one car not another.  $3 at radio shack and some time soldering, etc.  The wires are stainless so I made small crips by removing the plastic shields and ends off plain eyelets.

51 minutes ago, Zeke said:

Bad 02 sensor.

Is there any wat to test them?  I would think they will have a standard output range in mA/mV/Ohms when functioning properly?  

32 minutes ago, jm1827 said:

Is there any wat to test them?  I would think they will have a standard output range in mA/mV/Ohms when functioning properly?  

You tube it.... a quick search find a plethora of vids. Good luck and keep us updated.

12 hours ago, Zeke said:

You tube it.... a quick search find a plethora of vids. Good luck and keep us updated.

Yea- thanks

 

It's probably the cat.   I've never had a non-oem cat last any length of time.  If you're selling the vehicle soon, buy the cheapest one you can find, if not buy the Honda oem.  You can do it yourself, that said, every car I've ever messed with the exhaust on has had rusted bolts, so a pneumatic grinder to cut the bolts or a torch is often necessary.   

It's WAY easier on a lift, but I've done it on my back laying in my gravel driveway.

 

 

 

Thanks Malsua, Since I don't plan on selling it I will go with the Honda OEM cat.  I will probably try changing it myself.