Codes Codes Codes

[BenO]

My car threw some codes and when I wen to check got:
1. P0136 - Oxygen O2 Sensor Circuit Low Voltage (Bank 1, Sensor 2)
2. P0440 - no description needed
3. P0446 - Evaporative Emission Control System Vent Control Circuit Malfunction
4. P0463 - Fuel Level Sensor Circuit High Input

For the O2 sensor, the rear sensor on my Cat has a tendency to rattle loose and fall out for some odd reason so I think that is the cause of that one. I have yet to go back and see if it is still there after I have cleared it and the sensor hasn't come out.

Both evap ones I am lost on. The P0440 has been constantly going off since I got the car a few years ago and I had the fillerneck replaced which was rotten out. I heard replacing the purge valve might help, any evidence of this? and does anyone have the part number on hand if it does work?

The fuel level sensor I don't know how to fix. I have noticed my gas gauge going from 3/4 to empty then back up so I figure that has to be part of the problem.

So any help on any of these would be fantastic.

[jey]

Yeah with the circuit malfunction on the purge control valve I'd replace that solenoid.

[BenO]

well, found out that the purge control valve and the PCV valve are two entirely different things with about a hundred dollar price difference. on a good note, my PCV valve has been replaced

[ouch1011]

PCV stands for positive crankcase ventilation...it vents oil vapor and crankcase pressure out of the crank/oil pan area on the engine. EVAP system vents fuel vapor/pressure from the gas tank.

The rotted out fuel filler neck seems to be a common Subaru problem.

Testing for the P0440 according to Subaru is to connect the green 2-pin test mode connector under the driver side dash, turn the key on, and then go to each of the various EVAP system solenoids and listen/feel for them clicking on/off. Purge solenoid is mounted under the intake manifold on the passenger side, all the other solenoids are mounted near the charcoal canister (on the sedans, which have the canister under the pass side rear bumper, but I know the canister is under the hood on the wagons, so I don't know if the solenoids are with the canister or not). Since you have a vent solenoid code, I'd start there, because the vent solenoid is there specifically to close off the EVAP system for testing.

Additionally, with the fuel level sensor code, if the fuel level sensor is reading the fuel level incorrectly, it will cause the engine computer to miscalculate the volume of air in the fuel tank, and throw off its calculations, which are used to determine when to run the EVAP tests and what size of leak it has detected. So realistically, if the fuel level sensor is reading incorrectly, that needs to get fixed before anything else, because it can cause false EVAP codes.