Recently, My car has thrown the P0446 code. It had done this once before about two years back. I had the code cleared back then, and it hadn't come back until last week. I tried clearing it again, and it came back two days later. Just for good measure, I again deleted the code and it came back again, two days later. This is my daily driver and i put at least 30 miles on the car every single day. I know that getting this code could mean any number of things. The only weird things I have noticed are that my battery gauge will often jump from 14 volts down to below 12, then back up again intermittently when I am downshifting, or when shifting into neutral while pressing the brake coming to a stop. When idling while warm, the gauge will usually slowly drop down to around 13 volts. The gauge also will occasionally shake back and forth when at 14 volts. The clutch pedal also seems to change the point at which it engages when the voltage lowers. I have checked all the main grounds on the car. I also notice that it will run intermittently. Sometimes the engine sounds completely normal while I am accelerating and shifting gears, other times it will make a whistling sound when pressing the gas similar to a vacuum leak. The last thing I've noticed is that the exhaust makes a rattling sound more often than not, especially when decelerating or at lower rpms. Not sure if this has anything to do with the code but i figured I should list everything just in case. All of this has been going on much longer than the check engine code but I cant seem to pin point it, and have all but given up at this point. I feel like my car is possessed! It doesn't seem like there is a loss of power at all and I have had no other issues with this car at all. Any help/input is greatly appreciated.

 

The DTC P0446 is for a problem in the Evaporative Emissions Vent System. Could possibly be a vent valve stuck closed, kinked hose or plugged EVAP canister. I've attached a wiring diagram, troubleshooting chart and EVAP System diagram, but you may have to have access to a Tech 2 scanner to troubleshoot with the chart.

 

catalytic converter may be going bad, clean battery posts and cable ends, wire brush the heck outa them. have alternator tested. may want to have a look at the ignition switch, its down the column by the clutch peddle.