I have 2 android phone based scanners, Torque and OBDlink, let me go fire them up and see which one has the tank pressure.

 

In my 08 H2 I used Torque Pro to log the Evap Pressure when I was diagnosing my P0455 issue so I know it will work for the 08 model

Neal

 

Does anyone know if you can read the tank pressure with a Tech2?

 

Yes, the Tech2 will allow you to view and manipulate the solenoids and pressure

You have full control of the system with a Tech2

 

Hi! I'm chasing P0446 myself and have to find the vapor canister to check the solenoid valve.

Can someone point me to where I can find the canister?

 

On the 08 & 09 its tucked up under the drivers side between the frame rail and the body

 

Thank you legerwn!

Turns out I was really looking for the canister vent solenoid, which is mounted up above the gas tank behind the left rear wheel. I removed it and bench tested it and it made clicking noises on 12V, so I reinstalled it.

The next part to check is the purge valve in the engine bay.

Other than OBDII code P0466, I started having trouble when filling the tank... it will only take a gallon or so before the pump starts shutting off, which suggests that something isn't opening to collect or vent the vapor pressure in the tank.

Are any of these parts known to fail more often than others? It's a 2008 H2 with ~130k miles on it.

 

The vent solenoid has a filter on the inlet which will plug and can cause the issue of slow filling also the canister can get clogged and will cause the same issue.

When you had the vent solenoid off did you take the filter out and clean it?

 

I did not see a filter on the solenoid inlet. I am inclined to just replace the solenoid if I have to go in again.

Btw, I did a couple of short (<10 mile) drives after toying with it all and while I did not get another CEL yet, I did still have problems filling the tank, so clearly my problem is not solved.

I can get a new GM canister from Amazon for $90 delivered so I will replace that and the solenoid. Should I replace the valve in the engine bay as well?

 

For the slow fill issue I would start with the canister and vent solenoid.

My canister was packed solid, no rattle when i took it off, i blew it out and knocked it around a bit untilnthe carbon was loose again then re-installed it and my slow fill issue got a lot better. I also cleaned the filter in the vent solenoid.

The filter is inside the solenoid, there are some small clips around the top of the solenoid you need to pull them up and pop the top off to find the filter.

Replacing both is the best option