EVAP Code P0496

GT Envy · Oct 23, 2015

So I have had a code coming on over the last few weeks, code P0496. It is listed as an EVAP code related to the purge valve (up by the oil fill in the passenger valve cover). All other threads I have read concluded with the OP replacing the purge valve which fixed the issue. Mine hasn't.

Troubleshooting so far:

First, I simply cleared the code with HPTuners to see if it came back. Well, it did.
Next I tried tightening the gas cap. It was fine, code still is on.
I then checked voltage at the electrical connection for the solenoid. The voltmeter read 12Volts. This was with the ignition in run, but car off. This brings me to my first question, when the valve is normally closed, is 12V normal?
I then used the HPTuners scan tool to check the canister solenoid valve (one back by the tank), I could here the relay open and close, no problems there. For some reason, the scanner option for the purge valve test was greyed out.
So without testing it, I replaced the purge valve and erased the code. A day later the code came back. Grr!
I read the repair manual for the car, it states that the code P0496 is lit when the purge valve state doesn't match what the car commands. Apparently, P0499 is exclusive to the canister solenoid valve, which I verified to work. I am now at a loss.
The repair manual just mentions a bunch of tests which need weird GM scan tools ans such.
Could I have a wire connection loose? What else can I check? Any other ideas before I give up and go to my mechanic?

BAS G8 · Oct 24, 2015

Had same P0496 code on my V6 two weeks ago, changed mine out a dealer, cleared problem right up.

As far as weird scan tools as far as I know they code scanned with a GM Tech 2 to confirm what my sons aftermarket scanner said.

GT Envy · Oct 28, 2015

Correction: Code is P0443.

Any ideas on what else to test?

GOPHERIT · Oct 29, 2015

The purge valve is powered up at all times when the ignition is turned on. The valve will be pulse width modulated open and close whenever the ECM commands it (by producing a cycling ground potential). The voltage is supplied by the F33-15A fuse in the underhood fuse box, labeled (EMISSIONS 1). It powers up that purge valve and your DOD circuit. If that DOD is operating correctly, forget about that fuse as the source (but could be a wire breakdown before it gets to the purge valve itself). If its been turned off/deactivated, you might have a power source that's not capable of supplying 12 volts under load, but could easily read 12 volts with a meter. That P0443 code, pretty much says its sensing some type of problem with the 12 volts to that valve.

GT Envy · Oct 29, 2015

I deleted all Dod hardware, so there is possibility that the fuse is out and I wouldn't otherwise know. A resistance check from the fuse box to the connector at the valve should allow me to determine if the wiring itself is bad.
Thanks for the ideas!

GOPHERIT · Oct 29, 2015

More checking shows that (that) F33-15A fuse, also powers up the heaters within both upstream H02 sensors. Since you don't have the check engine icon illuminated, that pretty much eliminates that fuse.

GT Envy · Nov 13, 2015

Mechanic diagnosed the issue as the driver in the ECM being failed which causes the purge valve to be open permanently. Looks like I won't be running the EVAP purge circuit anymore, because I am not buying a new ECM. The purge valve is not necessary to properly vent the gas tank anyway. Only purpose is reducing emissions; not exactly my car's strong point anyway...

WhiteHotG8GT · Nov 13, 2015

GT Envy said:
Only purpose is reducing emissions; not exactly my car's strong point anyway...

Here's your sign. :wall:

[ame]http://www.amazon.com/Chrome-Finish-Emblem-Diesel-Letter/dp/B00QF0G75Q[/ame]

BAS G8 · Nov 13, 2015

Ouch, my fix was $130 or so, I don't even want to think what an ECM might cost.
I take it your state does not have a clean air program, up here a code stored on your ECM would be a fail therefore no annual licence plate sticker.

mvp5000 · Nov 14, 2015

I had that code or similar and ended up being the Vent Solenoid which ended up being like 725. They said had to drop the rear end.

EVAP Code P0496

Our Vendors

Top Contributors this Month

Recommended Communities