P0447, P0422

Japedo · Post by **Japedo** » 14 Nov 2009, 05:08

Hello folks, I am 2 codes away from having my check engine light off "P0447 Evaporative Emission Control System Vent Control Circuit Open"
"P0422 Main Catalyst Efficiency Below Threshold Bank 1"

I understand that the charcoal cannister and the hoses involved can throw the evap code. BUt i have never troubleshooted the evap system before.
I also understand that my 0422 code could be a bad o2 sencor or possibly the cat itself?
Anyone who has solved these codes or has any input would be great, im going to keep searching and i'll update this thread when I make some progress.
THanks to all
Curtis
94 850 turbo
01 V70 XC

Doug S · Post by **Doug S** » 14 Nov 2009, 13:22

For the P0447 code check the EVAP vent valve located on the upper fan shroud, driver side (for my car anyway 2001 V70). This is a solenoid valve with two vacuum lines and a 2 wire connector. If you have a meter check the valve for an open, this is an open circuit code. It could also be the connector, wiring or the fuse but if were the fuse you would likely have other problems, the fuse supplies power for several other things. The circuit is one signal from the ECM to the solenoid to power. The ECM provides a ground to activate the vent valve and is sensing the circuit is open.

I can't help much with the p0422 other then recommend going to someone that can read the two 02 signals and at least determine if it's one of the 02 sensors or the converter or possibly something else. Since the O2 and CC are expensive parts it would be good to know exactly which part is causing the problem.

http://www.autoshop101.com/forms/h64.pdf

Japedo · Post by **Japedo** » 14 Nov 2009, 14:56

Thanks alot doug, thats some great guidance on the p0447 code. I do have a voltage meter and will use it to try and find the open circuit. Sounds like you may have dealt with this sort of tihng yourself.
As for p0422, I will have to bring it to a local garage where they can read some live data. Ive been saying forever that i am going to setup my laptop for this but haven't yet, maybe christmas.
Thanks again.

Curtis

Doug S · Post by **Doug S** » 14 Nov 2009, 17:15

I do have some experience with the EVAP canister vent valve. I had a P0445 code which is a shorted condition for this valve circuit. It turned out to be a bad (shorted) capacitor on the ECM board, I was lucky and actually able to repair the ECM. Hopefully your open circuit issue is just with the solenoid itself or the wiring, which I suspect is the case.

ctrobk · Post by **ctrobk** » 16 Nov 2009, 19:33

I had the P0422 code on my 03 V70. I kept resetting the light and eventually it stayed off. However, performance kept degrading until it got so bad, I was having trouble going up hills. The degradation was gradual, so I didn't notice it at first.
It turned out to be the CAT. Luckily my local shop was able to get a salvaged one for about $450. However, CATs are covered by the emissions warranty for 8 years/80k in most states. CA might be 100k. Mine had about 87k when I had to replace it.
Someone else on the forum might be able to clarify this, but I think all major emission items ie. CAT and ECM are under this warranty.

I just replaced my rear O2 sensor which was throwing a code. About $180 from FCP Groten for a direct OEM replacement. $12 for a O2 sensor socket and the job was pretty simple. Saved probably $200 from dealer price according to some other posts on this issue.

JohnnyO · Post by **JohnnyO** » 03 Jun 2011, 20:21

Hi Guys, I have a 2001 v70 T5 and also got code P0447. The EVAP vent valve is more accurately called the Pierburg Purge Valve which can be ordered from partsgeek.com or autopartswarehouse.com. I replaced the old one and Voila! no more check engine light. I passed the NJ state insp. yesterday. JohnnyO