It may be one of the other cats. I believe there are three on the HCH1? Is the car running OK. It is possible you have a bad cat. If it is performing OK just ignore it. Lots of folks are! H

 

It has two (2) cats and three (3) O2 sensors. I have replaced the first and third O2 sensors.

It is running great.

Can I do the spark plug extender mod without hurting anything?

tja

 

Never done it myself so cannot really say! Try goggling it. I would put a pcs. of tape over the light. H

 

I had my 2003 HCH updated with software around October 1, 2011 because of the persistent P1420 code problem. It went away for about 2 weeks then reappeared...But, it went away miraculously about 2 weeks ago for unknown reasons. Maybe the software took that long to bring down the threshold levels concerning the catalytic converter. Anyway, I wanted to share my experience with this persistent problem. It's been driving fine, but it sucked having the check engine light on all the time.

 

I Just recently bought my car(2003 civic hybrid) and I just had the same code come on. I cleared it, and it came back on the next day during my 70 mile commute to work. Do you guys know if there is a way I can see if my software has been updated without going to the dealer?

 

Never mind. I just called the local dealer and they said it hasn't been done, along with some other recalls. They said I can bring it in at anytime for the repairs free of charge!!