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My 03 CRV had a p0420 catalyst below efficiency yesterday.
I followed a Honda bulletin about it and:
1) no exhaust leaks
2) voltage measurements of secondary sensor are normal.It then just says, “return car to owner”.
Well, if everything is fine, what set off the p0420?
I’ve driven 8 cycles since I cleared the code. It hasn’t come back yet.
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Lol. I ask the question, and ECTG comes out with a video a day later? Awesome!
Yes, my secondary O2 reads out steady at 0.65V when the car is at crusing rpms, it drops to 0 on deceleration.
According to what Honda says, it should be between 0.5 and 0.8 at crusing and less than 0.1 at deceleration.
And if the voltages are ok, apparently it’s not necessary to check the inlet and outlet temperatures.
Therefore, the cat is okay. But then I’m at a loss as to why the p0420 came on. Could a rainy day mess with the sensors?
It’s not likely the sensors. I would check the temps and then see what you have to verify that as shown in the video. If it’s an aftermarket cat this is likely the cause as they don’t work well on most cars and often set a P0420.
Followup: It’s been almost 3 months since the first time, and I had one recurrence of the p0420 about 2 months ago, also again on a rainstorm day.
I checked again for exhaust leaks, none. Volatges were the same, in the normal range. Checking the cat temperature showed 400F pre cat and 540F post cat.
It’s been 1500+ miles since the second time p0420 came on.
It’s the original cat, 180K miles.
Followup again.
P0420 again, seems to come on once every 3 months. Lol. About 8500 miles since last time the loght came on.
Again, no exhaust leaks. Voltages around 0.65 crusing, drops to below 0.1 on deceleration.
Cat temperature 430 precat, 580 postcat.Went to a smog inspection. Passed. car is emitting virtually no smog on their sniffer. HC and CO are near zero, far below the average car, and far far below smog limits.
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