Reading evap pressure sensor voltage

[jsm10]

I am hoping someone can help me.  I got a P0446 (vent valve circuit) on my 2007 Silverado classic (GMT800).  Replaced the vent valve solenoid because I thought it was sticking when testing with a 12V battery charger.  Tested the purge valve - OK.  Gas cap gasket looks good.  Took the vent valve hose off and blew pressure into it.  Held thumb over it for 60s.  Air whooshed back out.  So, I think it could be the fuel tank pressure sensor.  Is there a tool I can buy to read the live data on the sensor voltage?  I read that an ELM327 WIFI OBD2 adapter and the iOBD2 app will, but not sure.  Any recommendations on a scan/diag tool or an OBD2 reader with app to do this?  Thanks in advance.

[Jsdirt]

I wouldn't do too much EVAP testing with compressed air. The system max pressure is about 2 psi - about what you could do blowing into it. Also, 12v is much higher than that component is designed to operate on. It's supplied with a 5v reference from the computer.

 

I can't tell you specific scan tools that can do it, but I'd wager any scan tool, even the cheap small ones with live data should be able to read sensor voltage. I have an Autel 906TS that can read it, and prior to that my old AutoXRay AX7000 handheld could read it, too.

 

Are you sure the vent valve wiring is good?  Good 5v reference, and signal back to the ECU? Canister isn't plugged full of dirt? I'd do a few more checks before condemning the pressure sensor. Always best to be 200% sure.

 

EDIT: Memory is a little foggy on the vent valve - that may very well be 12v. Can't recall at the moment.

Edited August 21, 2021 by Jsdirt

[jsm10]

Thanks.  Going to try the "Torque" app and see if that will do it.