Po442 and po496 at the same time After repairs!!!
January 3rd, 2018, 9:30 PM
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Po442 and po496 at the same time After repairs!!!
Hello New here with a problem that’s not going away.
2007 lt tahoe
I have po442 and po496
it started with po442 a while ago. The dealer sold me a car and accidentally canceled my auto warranty and the check engine came on. So they repaired it for free. Said it was purge valve and said I shouldn’t use anything less that 91 gas on it. So I researched and found nothing on having to use 91 gas. He said I shouldn’t use anything lower unless I was “planning on racing that bad boy” made no sense so I just put 89 in case. Anyways po442 came up shortly after that and after research I ordered the evap purge solenoid complete with hoses and replaced the part underneath the spare tire on the 2007 lt tahoe. And it came on again. I looked underneath the spare tire area and saw a crack in the brand new hose of the complete canister part so I returned and got a new one this time from autozone. Replaced the part and then po496 comes on. So I get the purge solenoid and replace that located on top of engine underneath the engine cover. Twice now actually 3 times. And now the po442 and po496 are both on and I can’t figure out what the heck is going on. I replaced both parts 3 different times. What else could it be? Thanks for your help
2007 lt tahoe
I have po442 and po496
it started with po442 a while ago. The dealer sold me a car and accidentally canceled my auto warranty and the check engine came on. So they repaired it for free. Said it was purge valve and said I shouldn’t use anything less that 91 gas on it. So I researched and found nothing on having to use 91 gas. He said I shouldn’t use anything lower unless I was “planning on racing that bad boy” made no sense so I just put 89 in case. Anyways po442 came up shortly after that and after research I ordered the evap purge solenoid complete with hoses and replaced the part underneath the spare tire on the 2007 lt tahoe. And it came on again. I looked underneath the spare tire area and saw a crack in the brand new hose of the complete canister part so I returned and got a new one this time from autozone. Replaced the part and then po496 comes on. So I get the purge solenoid and replace that located on top of engine underneath the engine cover. Twice now actually 3 times. And now the po442 and po496 are both on and I can’t figure out what the heck is going on. I replaced both parts 3 different times. What else could it be? Thanks for your help
January 4th, 2018, 8:06 AM
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p0442 sets when a small leak is detected. it determines the leak using data from the fuel tank pressure sensor
p0496 sets when the vehicle detects purge flow during non purge conditons. it determines this using data from.....wait for it...the fuel tank pressure sensor.
neither code should run its test if the other code is set. clear the codes with a scan tool and see which returns. diagnose for that code.
if the returned code is p0496
with a scan tool...monitor the ftps data...with the cap off it should be near 0"h20. during purge condtions pressure should drop.
1. Start the engine.
2. Seal the EVAP system using the Purge/Seal function with a scan tool.
3. Observe the FTP sensor with a scan tool. The Fuel Tank Pressure Sensor parameter should be less than 1.7 volts after 90 seconds.
- If the Fuel Tank Pressure Sensor parameter is greater than the specified range, replace the EVAP canister purge solenoid valve.
if you see no change in the sensor value...there may be a sensor or sensor wiring problem
if the returned code is p0442 you need to leak test the system with a evap leak detector
if you can't do either due to lack of scan tool or leak tester and want to take a guess...replace the fuel tank pressure sensor and inspect the connector for corrosion. It sits on top of the fuel tank sending unit.
p0496 sets when the vehicle detects purge flow during non purge conditons. it determines this using data from.....wait for it...the fuel tank pressure sensor.
neither code should run its test if the other code is set. clear the codes with a scan tool and see which returns. diagnose for that code.
if the returned code is p0496
with a scan tool...monitor the ftps data...with the cap off it should be near 0"h20. during purge condtions pressure should drop.
1. Start the engine.
2. Seal the EVAP system using the Purge/Seal function with a scan tool.
3. Observe the FTP sensor with a scan tool. The Fuel Tank Pressure Sensor parameter should be less than 1.7 volts after 90 seconds.
- If the Fuel Tank Pressure Sensor parameter is greater than the specified range, replace the EVAP canister purge solenoid valve.
if you see no change in the sensor value...there may be a sensor or sensor wiring problem
if the returned code is p0442 you need to leak test the system with a evap leak detector
if you can't do either due to lack of scan tool or leak tester and want to take a guess...replace the fuel tank pressure sensor and inspect the connector for corrosion. It sits on top of the fuel tank sending unit.
January 4th, 2018, 5:16 PM
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Thanks for the reply man.
I must admit the steps are a bit out of my league but great info it just may take some time to complete.
i wanted to mention I had the whole fuel sending unit replaced by a mechanic and I kept the old part because he told me the sending unit was fine just the fuel sensor was bad as I was experiencing wrong fuel reading in the dash. Since then the fuel reads right but still po 496 and po 442 won’t go away.
I must admit the steps are a bit out of my league but great info it just may take some time to complete.
i wanted to mention I had the whole fuel sending unit replaced by a mechanic and I kept the old part because he told me the sending unit was fine just the fuel sensor was bad as I was experiencing wrong fuel reading in the dash. Since then the fuel reads right but still po 496 and po 442 won’t go away.
January 4th, 2018, 11:52 PM
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I figured it out man,
i took the old evap canister purge solenoid complete part back off the truck and inspected. Turns out the canister with the two nipples leading to hoses had a small -not a crack- but looked like it was connected using a epoxy glue (the nipple that attaches to hose) and it looked like a small part of the epoxy glue that held it together was missing. It wasn’t a crack it was a small part of the canister that looked like was put together with epoxy glue and a small very small part as wide as a flathead screwdriver was missing the glue. So I bought some epoxy plastic weld stuff and repaired that little hole. Put it back together and all is good now check engine is off. I bought that part at a chevy gm dealership. Drove me crazy. Thanks for your help dude.
i took the old evap canister purge solenoid complete part back off the truck and inspected. Turns out the canister with the two nipples leading to hoses had a small -not a crack- but looked like it was connected using a epoxy glue (the nipple that attaches to hose) and it looked like a small part of the epoxy glue that held it together was missing. It wasn’t a crack it was a small part of the canister that looked like was put together with epoxy glue and a small very small part as wide as a flathead screwdriver was missing the glue. So I bought some epoxy plastic weld stuff and repaired that little hole. Put it back together and all is good now check engine is off. I bought that part at a chevy gm dealership. Drove me crazy. Thanks for your help dude.
January 5th, 2018, 12:26 AM
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This whole evap system check engine has been going on for 2 years. Since I took it to busybee mechanic shop on spring mountain in Las Vegas. They charged my warranty $1600 and check engine came back on that’s when I took it to the Mini Cooper dealer I think it’s an automation in Las Vegas on Sahara street. Since they accidentally canceled my warranty they agreed to fix it and said it was the purge valve and said had they charged me it would have been $700. Check engine came back again and by this point I researched the engine codes and found the parts for less then $100 total. This included the purge valve and the evap canister solenoid. Only to have purchased a defective solenoid causing the check engine to go off again. Busy bee didn’t do anything. Mini Cooper pretended the did a heart surgery so to speak. In reality none of them did ****. Then just my luck I purchased from chevy dealership in Las Vegas and it’s a defective part. Just needed something to seal a very very smal part of the canister. 2 years of my life wasted and countless dollars lost in the pockets of these guys. Wow. Thanks sin city.
January 5th, 2018, 8:27 AM
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that makes sense for the p0442 code ie small leak but not the p0496 purge during non purge conditions.
Last edited by tech2; January 5th, 2018 at 9:40 PM. Reason: grammar
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January 5th, 2018, 8:50 AM
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What I did was I went to orileys auto where the purge valve was under warranty I got that warrantied out and then I took the evap purge canister to autozone where I thought I purchased from and they couldn’t find in their systems and as I inspected the canister I found the culprit plastic welded the small leak area and got home and installed both parts and drive for 15 minutes engine light off feels good no issues now. I’ll update if I’m wrong going to be using the car to drive rideshare tonight so I’ll be putting a healthy amount of miles on the car.