CCV Troubleshooting

Hello, i have a 2008 Kia Spectra 5 SX Hatchback giving me this code.
I have a po449 . It's a ground side switch, it has 12v to the power side with the key on. I have a bidirectional scanner so i have actuated it and the
valve works but it is humming. I have back probed the control / ( - ) wire with my test light and the light comes on when i actuate the valve.
But when i turn the valve off the light stays on just slightly. That's a short to ground right ? If i unplug the harness from the valve it does not make the light go out.
I ran a temp wire from the ECM to the valve thinking maybe the control wire was bad but nothing changed. Can the driver be shorted but still sending a signal ?
If you could help it would be highly appreciated.
Thank you, RalphD66

The test light behavior you described does sound a bit odd. :huh: Was your test light connected to B+ when you bidirectionally controlled the vent valve? Is it incandescent or LED? If you turn the key off, does the light go out completely?

Not trying to dictate your diagnostic direction, but P0449 does not necessarily point to a vent circuit problem. From service information:

The ECM measures pressure in the fuel tank by means of tank pressure sensor during all engine operating states except engine stop and start. The DTC P0449 is set if pressure is lower than predetermined threshold.
If same error code is set in the next driving cycle, the ECM illuminates the MIL.

It's really describing a mechanically stuck closed CCV *OR* a vent path restriction. Vent filter plugged, canister restricted, like that. I commonly see this code on Kia/Hyundai vehicles that are driven on gravel roads. Some get fixed with just the canister air filter (the filter before the vent valve), others need the filter and the canister assembly. P0447 and P0448 apply specifically to open/short conditions in the vent circuit.

Yes the light was connected to B+ at the battery itself and at B+ on the connector tp the valve.
Either way i have the same results. It's incandescent. Key off the light goes out.

Ok i will check to see if there is 12v on both wires when the key is on.
I'll let you know what i find
Thanks for your help.

I re-checked and the light stays on with the key off. I can take the key out and the light stays on.
Just to be clear, i put the test light clamp to the + on the battery itself. I back probed the ( Blue) control wire.
I turned the valve on with the scanner and the light comes on. I turn the valve off and the light goes out, but
stays on just slightly. And the light don't go out when i turn the key off.
And if i unplug the valve the light don't go out so i'm thinking either a shorted wire or driver.
I ran a temp wire from the ECM to the valve in place of the blue control wire. It makes no difference.
If i unplug the ECM the light goes out. So i'm thinking shorted driver. Unless i'm missing something.

Test light results are unusual but might be normal for that vehicle?? Does bi-directional testing with the scan tool point toward a problem with the vent valve control?

Bidirectional control has shown that the circuit and valve are actually working.

I will do some double checking but it looks like that's the case. I will let you know what i find.
Thanks

RD66 wrote:

Bidirectional control has shown that the circuit and valve are actually working.

With the valve commanded closed, can you blow through it? With the valve commanded off (but still plugged in), can you blow through it? If you unplug the valve, can you blow through it?

Have verified with the valve commanded off, 12v on the hot side and 3.5 v on the control wire. Bench tested the valve it works fine. No humming. In the car commanded on it closes but hums. Shorted driver right ?