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Old 07-21-2022, 03:05 PM   #1
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P0444 EVAP failure

Hey Folks,

I got a CEL shortly after refueling. The code is P0444, indicating it`s an EVAP system related issue (“Evaporative Emission System Purge Control Valve Circuit Open.”) I don`t have issues with filling up the tank, no stalling. I haven`t mess with anything recently in the engine compartment. I erased the code but the CEL came on within 20 mins.

I searched around the web and the forum regarding this code and found multiple causes including gas cap, purge valve, charcoal canister, vent lines, etc. Is there a recommended route to take on exploring the potential culprits?

Thanks!

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Old 07-21-2022, 03:45 PM   #2
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Hey Folks,

I got a CEL shortly after refueling. The code is P0444, indicating it`s an EVAP system related issue (“Evaporative Emission System Purge Control Valve Circuit Open.”) I don`t have issues with filling up the tank, no stalling. I haven`t mess with anything recently in the engine compartment. I erased the code but the CEL came on within 20 mins.

I searched around the web and the forum regarding this code and found multiple causes including gas cap, purge valve, charcoal canister, vent lines, etc. Is there a recommended route to take on exploring the potential culprits?

Thanks!
I think the first thing to do is get a diagram of all related parts and hoses.
Then do some research to gain as much understanding as possible of how the system and related parts work.
Then with that... plan out a methodical step by step diagnostic procedure and prove each component of the system good or faulty. Starting with the simplest things first.
That is how I approach automotive issues.
The "EVAP" system is not complex but access to many of the components is the real issue.

From the code description you gave it sounds like the purge valve is stuck (open??) or there is an issue with the wiring to the purge valve.
I think the purge valve is in the wheel well behind the wheel well liner in the area of the fuel filler.... neck but I am not positive.

Last edited by blue62; 07-21-2022 at 03:51 PM.
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Old 07-22-2022, 06:08 AM   #3
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I think the first thing to do is get a diagram of all related parts and hoses.
Then do some research to gain as much understanding as possible of how the system and related parts work.
Then with that... plan out a methodical step by step diagnostic procedure and prove each component of the system good or faulty. Starting with the simplest things first.
That is how I approach automotive issues.
The "EVAP" system is not complex but access to many of the components is the real issue.

From the code description you gave it sounds like the purge valve is stuck (open??) or there is an issue with the wiring to the purge valve.
I think the purge valve is in the wheel well behind the wheel well liner in the area of the fuel filler.... neck but I am not positive.
The phrase "open circuit" is referring to the electrical circuit, indication of either no power or no ground.
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Old 07-22-2022, 07:05 AM   #4
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The phrase "open circuit" is referring to the electrical circuit, indication of either no power or no ground.
When there is an open circuit on the purge valve will the valve be open or closed??
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Old 07-22-2022, 07:33 AM   #5
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When there is an open circuit on the purge valve will the valve be open or closed??
Should be closed.
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Old 07-22-2022, 09:05 AM   #6
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Should be closed.
Thanks....
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Old 07-22-2022, 09:35 AM   #7
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Thanks Blue and JFP for the comments. I guess I`ll start with looking at the fuses. Considering all this happened after refueling and this is a 22 year old car perhaps the valve got physically stuck and that blew a fuse.
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Old 07-22-2022, 09:45 AM   #8
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Thanks Blue and JFP for the comments. I guess I`ll start with looking at the fuses. Considering all this happened after refueling and this is a 22 year old car perhaps the valve got physically stuck and that blew a fuse.
Keep us posted I always like to know end results.
Helps me learn more about not only the Boxster but all automotive systems in general.
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Old 07-22-2022, 10:30 AM   #9
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Thanks Blue and JFP for the comments. I guess I`ll start with looking at the fuses. Considering all this happened after refueling and this is a 22 year old car perhaps the valve got physically stuck and that blew a fuse.
Wiring issues are more often the problem.
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Old 07-24-2022, 12:10 PM   #10
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Wiring issues are more often the problem.
Literally. Turns out the CEL coming up shortly after refueling was a coincidence. Simply, one of the wires snapped off the purge valve. Easy fix. Thanks for all the input, it was really helpful!

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Old 07-24-2022, 06:14 PM   #11
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Literally. Turns out the CEL coming up shortly after refueling was a coincidence. Simply, one of the wires snapped off the purge valve. Easy fix. Thanks for all the input, it was really helpful!

Looks like it fairly easy to get to.

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