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Evaporative Emissions System

(2003 Jeep Liberty)
in Denver, CO on December 21, 2012
I am getting two codes for a large and small evap emissions leak. I have repaired the leaks, pressurized the system and verified there are no leaks. I continue to get the same two codes. Any idea why I would still be getting these codes?
Displaying 2 answers & 8 comments
Popular Answer
on December 22, 2012
have it scan tested and clear codes if they come back then you have more than one problem
on December 22, 2012
I have already done that. The same codes come back stating there is a leak in the system.
on December 22, 2012
What are the codes?
on December 22, 2012
P0442 & P0455. I have cleared the codes and they keep coming back
on December 22, 2012

Customer Concern:MIL on and codes P0442 and P0455 stored.
1. Check for a loose gas cap.
2. Check for a split hose at the canister.
3. Ground the center wire at the Leak Detection Pump (LDP). This is a White/Dark Green wire that goes to pin 10 of the Powertrain Control Module (PCM).
4. Disconnect the electrical connector from the purge solenoid.
5. Start the engine.
6. Smoke test the system for leaks.
Tech Tips:
The vent in the LDP is normally open so it must be manually closed before smoke testing. Some scan tools will also do this but the engine needs to be running either way to supply vacuum to the LDP.
on December 22, 2012
Well I actually disconneted the hose from the leak detection pump, pressurized the entire system and the system held air pressure. There are no leaks or at least nothing that would be characterized as a large leak. So given there are no leaks and the large and small leak codes keep coming back after I clear them, what else might be he cause?
on December 22, 2012
You must use a SMOKE GENERATOR properly to test the system not air pressure. This is the only way.
on December 23, 2012
It seems to me that as long as you can test that there are no leaks in the system however you do it would be irrelevant.
on December 23, 2012
If you can not understand the concept of using smoke generator than no one can help you.
I have 46+ years of experience. I DO KNOW WHAT I AM TALKING ABOUT. Lots of luck, you'll need it.
Oh, buy the way Merry Xmas.
on December 23, 2012
Air pressure cause damage to fuel tank pressure sensor , causing erroneous readings and setting codes??? (Just know on Honda , if you pressurize over 2PSI , you WILL damage FTPS)..........just a thought to add to the confusion.......Parts guy IS correct.
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