keegan6975

Hello all,
I have a 2003 CRV and the downstream O2 sensor is giving code P0420 cadalyst system efficiency below threshold (bank 1), I'm assuming the sensor needs replacing, so i'm wondering, I have a secondary O2 from my RSX base, will this work, can't find any info on this.. would help in the cost if it did..

Thanks

tech8

On later generation cars, P0420 will usually be due to the cat, not the O2 sensor.

hondamark35

agreed.

most of the time it's the cat. converter "wearing out" (becoming ineffective). if it's ever the case that the sensor is the issue, the safe bet is that the cat. converter is on it's way out too.

recently learned about some stuff called "Cataclean" that is meant to keep a catalytic converter "healthy" for longer. the theory of operation seems sound, reviews are good but I've not had first hand experience yet. may be worth a shot though. if it works you should be able to reset/clear your code and continue on driving while you save up for a replacement converter.

keegan6975

Thanks all for the reply,
I tried the spark plug non-fouler, but no work, code still came back, but I just had another code appear, P1259 Vtec system B1, failure 2, Vtec system failure ? now I have to search this one up.. lol


Thanks,

hondamark35

haven't looked this one up specifically, but I normally check the screen for clogs at the solenoid and confirm oil level is full whenever there is a VTEC code.