On a 2003 Buick Century, I am not getting enough voltage/amps to pull in the vent valve on the evap system. I'm suspeciting a bad relay. Where is it?

Asked by Feb 08, 2017 at 09:29 AM about the 2003 Buick Century Sedan FWD

Question type: Maintenance & Repair

I see voltage at the vent valve solenoid but it is not enough to pull in the solenoid to close the valve when the ignition is on. It closes fine if wired to the battery. I'm getting the P0446 code. Is there a relay that may be bad somewhere on the car?  Is this signal routed thru the Purge valve?

3 Answers


If you see voltage, but it is low, there is more than likely a bad connection, or the wire strands are breaking, usually at the plugins. Also a bad ground could be a cause. There is power so I don't think it is a relay. You can check your fuse boxes for any emissions related fuses or relays.

I've been doing a little research here. Looks like it just takes a hot power signal thru the 30A ECS system fuse to the vent valve solenoid, the PCM grounds it when the Ignition is on to cause the valve to close. There is anoter fuse between the vent valve and PCM which I need to check under the hood, but no control relays, as the PCM controls the switching. Your recommendation for broken wires seems the most plausible if the fuse is not corroded/bad. I will check that out. Thanks


Keep me informed, always like to know...

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