P0442 keeps coming back
September 12th, 2020, 4:42 PM
#1
P0442 keeps coming back
Back and forth 3x to dealer. Keeps coming back on. Changed gas cap, purge valve, charcoal canister. Had loose neck where i put gas in fixed that. When i put gas in it pops the gas handle like its full but its not. At wits end with this. Can anyone offer advice?
thank you
thank you
September 13th, 2020, 10:10 AM
#4
-the dtc is for a small evap leak.
-the slow fill problem is from a blocked evap vent path.
not sure if this is dyi but here is some info.
to run the p0442 test...the vehicle waits for an engine off condition, closes the vent solenoid to seal the system and monitors the fuel tank pressure sensor for a change in pressure. it expects to see a change in pressure due to ambient temp changes. a system that can't seal won't change pressure.
first thing a shop should do is flow test the evap system. they command the system closed and fill it with smoke. if the smoke machine flow meter ball drops to zero...no leak is present...the fault is due to something else that would cause the pressure not to change. a faulty fuel tank pressure sensor is one option. When the system is being filled by the smoke machine...the tech can watch the sensor value change. it should read 0 with the fuel cap off.
the blocked evap vent path may or not be related to the p0442. it needs to be fixed anyways so do it first and see if it fixes both problems. for the tank to fill correctly and to not collapse when the fuel pump is running...air must vent in and out of the tank. if the vent path is blocked it will cause a slow fill. the vent runs from the top of the tank to the evap cannister...out the vent valve...out the evap filter and filter hose. this entire path must be clear. evap filters are a maintenance item. if you drive in dusty conditions the filter should be changed yearly.
-the slow fill problem is from a blocked evap vent path.
not sure if this is dyi but here is some info.
to run the p0442 test...the vehicle waits for an engine off condition, closes the vent solenoid to seal the system and monitors the fuel tank pressure sensor for a change in pressure. it expects to see a change in pressure due to ambient temp changes. a system that can't seal won't change pressure.
first thing a shop should do is flow test the evap system. they command the system closed and fill it with smoke. if the smoke machine flow meter ball drops to zero...no leak is present...the fault is due to something else that would cause the pressure not to change. a faulty fuel tank pressure sensor is one option. When the system is being filled by the smoke machine...the tech can watch the sensor value change. it should read 0 with the fuel cap off.
the blocked evap vent path may or not be related to the p0442. it needs to be fixed anyways so do it first and see if it fixes both problems. for the tank to fill correctly and to not collapse when the fuel pump is running...air must vent in and out of the tank. if the vent path is blocked it will cause a slow fill. the vent runs from the top of the tank to the evap cannister...out the vent valve...out the evap filter and filter hose. this entire path must be clear. evap filters are a maintenance item. if you drive in dusty conditions the filter should be changed yearly.
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Becca Mitchell (September 13th, 2020)
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