EVAP Vent Solenoid Code - P0446
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Date: 2020-08-05
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Comments and reviews: 10
Jim
I have a very similar 2007 Cobalt (vs 2008. It has a P0446 code. I recently purchased it and it has had the code since then. I don't have a fancy scanner, but I'll keep checking what I can. I tried a new gas cap with no luck. I had noticed that while filling with gas it tends to shut off before it gets close to full. I pulled the charcoal canister off thinking it might be plugged, but I'm able to blow easily into any of the 3 ports. After blowing into each port, I cleaned the vent filter internal to the canister while I had it out, but it wasn't that dirty.
While I had the charcoal canister off I tried to blow into each of the three Lines that connect to the charcoal canister. The big Vent line is easy to blow into (just vents to atmosphere. I can't blow into the little Purge line, but that makes sense as the Purge Valve at the engine is N. C.
I then removed the gas cap and tried to blow into the large line that goes to the gas TANK, but it felt like I was blowing up a stiff balloon. It would build pressure and then blow back in my face. Look at 6: 04 in the video. This large line also has a Tee fitting in it that connects to a 3/8 line that goes up the fill tube and connects into the fill tube just below the restricter plate/gas cap. Maybe the large line to the gas TANK has a rollover valve or something with some restriction, but the 3/8 line probably does not. Is there a reason I can't easily blow into this TANK line, or is this a sign of a problem (blockage, etc?
If there is a blockage this could explain the shutting off while filling, and perhaps the P0446 Code.
reply
I have a very similar 2007 Cobalt (vs 2008. It has a P0446 code. I recently purchased it and it has had the code since then. I don't have a fancy scanner, but I'll keep checking what I can. I tried a new gas cap with no luck. I had noticed that while filling with gas it tends to shut off before it gets close to full. I pulled the charcoal canister off thinking it might be plugged, but I'm able to blow easily into any of the 3 ports. After blowing into each port, I cleaned the vent filter internal to the canister while I had it out, but it wasn't that dirty.
While I had the charcoal canister off I tried to blow into each of the three Lines that connect to the charcoal canister. The big Vent line is easy to blow into (just vents to atmosphere. I can't blow into the little Purge line, but that makes sense as the Purge Valve at the engine is N. C.
I then removed the gas cap and tried to blow into the large line that goes to the gas TANK, but it felt like I was blowing up a stiff balloon. It would build pressure and then blow back in my face. Look at 6: 04 in the video. This large line also has a Tee fitting in it that connects to a 3/8 line that goes up the fill tube and connects into the fill tube just below the restricter plate/gas cap. Maybe the large line to the gas TANK has a rollover valve or something with some restriction, but the 3/8 line probably does not. Is there a reason I can't easily blow into this TANK line, or is this a sign of a problem (blockage, etc?
If there is a blockage this could explain the shutting off while filling, and perhaps the P0446 Code.
reply
John
South Main you are such a great resource of auto troubleshooting info - thanks again. Now had a similar issue - different fix. Last couple of days we bought a used 06 COBALT. Lots of miles but good price. Test drive of the car showed no engine light, everything was OK, ran smooth and good. Next day the engine light came on, now I don't have the high end code reader you have that does all those tests, mine just shows the codes. First thing I had to do was figure why I had no power on the OBD port to my basic code reader. Like alot of vehicles this is powered by the 15 amp fuse for a cigarette lighter. Now even though this car didn't have a lighter, it still had a fuse for it and sure enough it was blown. I think it powered the AUX 12 volt plugin port as well? not sure - or at least the one on the dash. Any ways quick fix on that, new fuse and now the reader had power on the port. Codes came up as P0300 - misfire, P0446 the one we are talking about here, and P2101 throttle body position performance? Anyway I checked with YOUTUBE and of course went to yours first, and OH MY, well I guess lets get started. First I started thinking? We also just filled the tank with gas yesterday and the 446 code is related to venting I wonder if the gas cap is bad, removed and it looked brand new, Cleared off abit of grime on the seat and rubber made sure it was back on tight. Went in and cleared the codes and they did not return - still fine today. Just wondering what may have cause the misfire code and the TB position code? no worries right now as they have not come back either.
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South Main you are such a great resource of auto troubleshooting info - thanks again. Now had a similar issue - different fix. Last couple of days we bought a used 06 COBALT. Lots of miles but good price. Test drive of the car showed no engine light, everything was OK, ran smooth and good. Next day the engine light came on, now I don't have the high end code reader you have that does all those tests, mine just shows the codes. First thing I had to do was figure why I had no power on the OBD port to my basic code reader. Like alot of vehicles this is powered by the 15 amp fuse for a cigarette lighter. Now even though this car didn't have a lighter, it still had a fuse for it and sure enough it was blown. I think it powered the AUX 12 volt plugin port as well? not sure - or at least the one on the dash. Any ways quick fix on that, new fuse and now the reader had power on the port. Codes came up as P0300 - misfire, P0446 the one we are talking about here, and P2101 throttle body position performance? Anyway I checked with YOUTUBE and of course went to yours first, and OH MY, well I guess lets get started. First I started thinking? We also just filled the tank with gas yesterday and the 446 code is related to venting I wonder if the gas cap is bad, removed and it looked brand new, Cleared off abit of grime on the seat and rubber made sure it was back on tight. Went in and cleared the codes and they did not return - still fine today. Just wondering what may have cause the misfire code and the TB position code? no worries right now as they have not come back either.
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ChadCliff74
BAD PRESSURE SENSOR FOUND AND REPLACED, thanks to your instructional, THANK YOU! Easy for anyone reasonably adept with android devices to do a basic test to see whether the computer is getting useful feedback from the sensor. I used an 0BD2 bluetooth adapter (inexpensive on Amazon) paired to my android phone and using the the Car Gauge Pro app. I used the apps gauge for fuel pressure sensor and the voltage did not change when I blew compressed air loosely into the filler neck (blocking off opening isn't necessary or recommended. On my Montana the tank has to be lowered just to get to the sensor (located on top of fuel pump) so testing it this way was a great preliminary test. After changing the pressure sensor it was easy to make the voltage leap just as you said! I'm so happy to have this resolved. A persistent check engine light feels too much like defeat and failure for this factory trained motosports mechanic with 11 years experience and avid do-it-yourselfer.
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BAD PRESSURE SENSOR FOUND AND REPLACED, thanks to your instructional, THANK YOU! Easy for anyone reasonably adept with android devices to do a basic test to see whether the computer is getting useful feedback from the sensor. I used an 0BD2 bluetooth adapter (inexpensive on Amazon) paired to my android phone and using the the Car Gauge Pro app. I used the apps gauge for fuel pressure sensor and the voltage did not change when I blew compressed air loosely into the filler neck (blocking off opening isn't necessary or recommended. On my Montana the tank has to be lowered just to get to the sensor (located on top of fuel pump) so testing it this way was a great preliminary test. After changing the pressure sensor it was easy to make the voltage leap just as you said! I'm so happy to have this resolved. A persistent check engine light feels too much like defeat and failure for this factory trained motosports mechanic with 11 years experience and avid do-it-yourselfer.
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Nick
I had the same issue. I have a 00 lesabre and it threw a code for a evap fuel tank pressure sensor high circuit so I just replaced it(p0446 or p0457 something like that. I now have an intermittent p0440 code which is a general evap leak code. I am assuming that the sensor was bad, but now the system can actually detect a leak lol. Not to sure what it is. Dont have access to a fancy diagnostic tool. Im assuming its a venting problem thought because when the leak is detected and the light comes on it is when my tank is at around a 1/4 tank. When I go to fill up the tank and take the gas cap off i can hear air being sucked into the tank. I also found out when I have the car in the on position and the fuel pump is primed and I am filling up with that code on it cause fumes ( and gas when I am pumping) to be pushed out of the gas filler.
Any ideas anyone?
reply
I had the same issue. I have a 00 lesabre and it threw a code for a evap fuel tank pressure sensor high circuit so I just replaced it(p0446 or p0457 something like that. I now have an intermittent p0440 code which is a general evap leak code. I am assuming that the sensor was bad, but now the system can actually detect a leak lol. Not to sure what it is. Dont have access to a fancy diagnostic tool. Im assuming its a venting problem thought because when the leak is detected and the light comes on it is when my tank is at around a 1/4 tank. When I go to fill up the tank and take the gas cap off i can hear air being sucked into the tank. I also found out when I have the car in the on position and the fuel pump is primed and I am filling up with that code on it cause fumes ( and gas when I am pumping) to be pushed out of the gas filler.
Any ideas anyone?
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George
looks like I replaced my evap purge control valve when really I should have replaced my fuel tank pressure sensor. A rat must have chewed some wires in my car because I keep getting evap purge control valve circuit open and I see rat droppings. I went on replacing parts like a dingle. I should test the voltage to the purge valve to see if its even getting anything that will tell me if a rat ate the wires going to that. Any ideas?
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looks like I replaced my evap purge control valve when really I should have replaced my fuel tank pressure sensor. A rat must have chewed some wires in my car because I keep getting evap purge control valve circuit open and I see rat droppings. I went on replacing parts like a dingle. I should test the voltage to the purge valve to see if its even getting anything that will tell me if a rat ate the wires going to that. Any ideas?
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Mike
The Ford trucks we had used a similar system. Once I learned the relationship of the fuel tank pressure sensor, the vent valve, the purge valve and other components, it became easier to diagnose Evap problems. Then came the 2009 Dodge Avengers, with no shop, Internet, or documentation support. Luckily I only saw two of those!
Great Video!
reply
The Ford trucks we had used a similar system. Once I learned the relationship of the fuel tank pressure sensor, the vent valve, the purge valve and other components, it became easier to diagnose Evap problems. Then came the 2009 Dodge Avengers, with no shop, Internet, or documentation support. Luckily I only saw two of those!
Great Video!
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Whydoyou
Excellent Job! Your understanding on how the system operates is what lots of mechanics lack. I use to work with at a Chevy dealership with about 10 mechanics and my observation was that only about 2 -3 out of them were were really good at diagnosing the less common problems that needed to be dug into further. Some were only good at R&R.
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Excellent Job! Your understanding on how the system operates is what lots of mechanics lack. I use to work with at a Chevy dealership with about 10 mechanics and my observation was that only about 2 -3 out of them were were really good at diagnosing the less common problems that needed to be dug into further. Some were only good at R&R.
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GNX157
Couldn't you of done a quick test of the other solenoids and valves back there to lessen the chance of another code after the drive cycle? And also do a complementary smoke test to check for leaks before it left? Have to say as a customer, that's what I'd want, not just a warning there might be other codes waiting.
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Couldn't you of done a quick test of the other solenoids and valves back there to lessen the chance of another code after the drive cycle? And also do a complementary smoke test to check for leaks before it left? Have to say as a customer, that's what I'd want, not just a warning there might be other codes waiting.
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Alan
Eric - thanks for this video. THUMBS UP! I found that I had the exact same failure on a 2007 Saturn Ion with code P0446. The vent valve still ok and the evaporative fuel pressure sensor was frozen at 4. 90 V. The sensor was also warm to the touch - so i suspect that it had some sort of internal short going on inside.
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Eric - thanks for this video. THUMBS UP! I found that I had the exact same failure on a 2007 Saturn Ion with code P0446. The vent valve still ok and the evaporative fuel pressure sensor was frozen at 4. 90 V. The sensor was also warm to the touch - so i suspect that it had some sort of internal short going on inside.
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Eric
Hello Eric, My name is Eric, I'm the lead Master tech at A. T. S (Automotive Technical Solutions in Atlanta Ga. You have great and very detailed Repair Videos, keep up the good work. Plenty of Work here in Atlanta, respond back pls, maybe its time to expand to a new market here?
reply
Hello Eric, My name is Eric, I'm the lead Master tech at A. T. S (Automotive Technical Solutions in Atlanta Ga. You have great and very detailed Repair Videos, keep up the good work. Plenty of Work here in Atlanta, respond back pls, maybe its time to expand to a new market here?
reply
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