2001 Tahoe Evap Codes P0446 and P0442
June 23rd, 2023, 2:37 PM
#1
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2001 Tahoe Evap Codes P0446 and P0442
Hello, codes P0446 and P0442 seem to be a fairly common issue, but experiences seem to vary quite a bit. This one has my brain hurting for sure.
I have had a check engine light on since I bought the vehicle (2001 Tahoe LT 4WD) more than 2 years ago. Recently moving to a city with mandatory emissions, i need to get these codes fixed ASAP.
I have replaced the purge valve at the front of the engine, and canister valve at the rear of the vehicle (above the differential). I also ran a smoke test, from after the purge valve to the canister valve, but could not detect a leak there. Neither of these helped me clear the code.
Now here comes the weird part. From time to time, when it would rain in Western Colorado, I would have to drive through a bit of mud to get home and to work. When this would happen, the check engine light would clear. It would only come back on after going through the car wash. I looked in depth under the vehicle to see where mud could fling up and plug a leak, but haven't been able to find an answer. Has this happened to anyone else??? It is driving me crazy!
I have had a check engine light on since I bought the vehicle (2001 Tahoe LT 4WD) more than 2 years ago. Recently moving to a city with mandatory emissions, i need to get these codes fixed ASAP.
I have replaced the purge valve at the front of the engine, and canister valve at the rear of the vehicle (above the differential). I also ran a smoke test, from after the purge valve to the canister valve, but could not detect a leak there. Neither of these helped me clear the code.
Now here comes the weird part. From time to time, when it would rain in Western Colorado, I would have to drive through a bit of mud to get home and to work. When this would happen, the check engine light would clear. It would only come back on after going through the car wash. I looked in depth under the vehicle to see where mud could fling up and plug a leak, but haven't been able to find an answer. Has this happened to anyone else??? It is driving me crazy!
June 23rd, 2023, 4:40 PM
#2
both codes indicate a evap leak is present.
the pcm commands the purge valve open to create a pressure drop in the fuel tank...it closes the purge and monitors the rate of vacuum decay. if the vac drops to fast the dtc sets.
smoke tester...if you have one with a flow meter...monitor that rather than watch for smoke. command the vent solenoid closed and start pressurizing the system at the evap service port. When the smoke tester is filling the system the flow meter should show a high rate of flow....after a few minutes it should fill the system and the flow meter should drop to zero....if it doesn't drop to zero, you have a leak. find the leak by dividing the system in half and pressure test each side.
the pcm commands the purge valve open to create a pressure drop in the fuel tank...it closes the purge and monitors the rate of vacuum decay. if the vac drops to fast the dtc sets.
smoke tester...if you have one with a flow meter...monitor that rather than watch for smoke. command the vent solenoid closed and start pressurizing the system at the evap service port. When the smoke tester is filling the system the flow meter should show a high rate of flow....after a few minutes it should fill the system and the flow meter should drop to zero....if it doesn't drop to zero, you have a leak. find the leak by dividing the system in half and pressure test each side.
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Bshawn911 (July 1st, 2023)
June 24th, 2023, 4:23 PM
#3
I see u changed the canister and purge valve but I'm pretty sure one of those codes is for the vent valve solenoid. Have you tried changing it out. I have a 01yukon and I have both them codes and have been wanting to fix but it has 338,000 miles. So I don't know how much time and money i want to put in it. *you could also check your vacuum lines from like the pcv valve just to make sure they are not leaking
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