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Ask Peter Bagley Your Own Question
Peter Bagley
Peter Bagley, Toyota mastertech
Category: Chrysler
Satisfied Customers: 730
Experience:  master tech at Toyota dealer
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Reading code PO440 Evap Leak, reploaced gas cap with new

Customer Question

reading code PO440 Evap Leak
JA: How old are the hoses? And what driving conditions do you most often encounter?
Customer: reploaced gas cap with new factory one,
JA: What is the model/year of your Chrysler?
Customer: 2007 chrysler pacifica 4.0 engine
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: like to try gas cap did not cure problem, light came back on after a couple of days
JA: Anything else you think the mechanic should know?
Customer: 70,000 miles on vehicle very good shape
Submitted: 1 year ago.
Category: Chrysler
Expert:  Peter Bagley replied 1 year ago.

hello my name is ***** ***** thanx for allowing me to help you. first off that code P0440 is a general evap code for possible leak, but could be related to items such as vsv vales stuck and not working and the vales inside the charcol canister, to find out id these are all working and to trace a leak is quite the process. One needs to hook up a shop scanner to it so you can do an active test on all aspects, when you do this it will monitor and show it's performance if all is creating vaccums and holding when it should allowing you to pinpoint the area. The next thing is if a leak is detected you hook up what we call a smoke machine to a service port on the evap system . This puts low pressure smoke into the evap system and allows you to physically see where the leak actually is. So you can see this is quite the process.

P0440 CHRYSLER - General EVAP System Failure

Possible causes

- Missing or loose fuel cap
- Incorrect fuel filler cap used
- Fuel filler cap remains open or fails to close
- Foreign matter caught in fuel filler cap
- EVAP canister or fuel tank leaks
- EVAP system hose leaking
- Fuel tank leaking

P0440 Chrysler Description

The Engine Control Module (ECM) tests the Evaporative Emission (EVAP) system for the following conditions:

- Large and small leaks

- Excess vacuum

- Purge flow during non-commanded conditions

- Fuel Level and Fuel Pressure sensor faults

- EVAP Purge and Vent Valve faults

The ECM monitors the Fuel Tank Pressure sensor in order to determine the level of vacuum/pressure in the EVAP system. The ECM commands both the EVAP Purge Solenoid and the EVAP Vent Valve ON when the conditions are met in order to apply an engine vacuum to the EVAP system. The ECM commands the EVAP Purge Solenoid OFF once the system has reached a predetermined level of vacuum. This test verifies if a vacuum can be achieved in the EVAP system. Failure to develop a vacuum may be caused by a large leak or a restriction.

Customer: replied 1 year ago.
Thank you for your help most of the info you sent i already got off the internet,
but i did take it to PEP boys for the smoke machine but they said there was no
provision on the 2012 Pacifica to use the smoke test. They checked for any leakes
without the smoke test and could not find any,.......suggested chrysler dealer may have provisions
to test but thats what i'm trying to avoid .......
Expert:  Peter Bagley replied 1 year ago.

well if the codes tell us there may be a leak in the system you must do a smoke test or it's like shooting in the dark and guess work . The only other test you can do then is with a shop scanner to do active testes and testing the vsv valves. like I said it's a high tech complicated system that needs proper active testing and diagnoses procedures. hope this helps you further , proper and diagnose procedure is a must for this system . Hope this helps.