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Ron Z.
Ron Z., - Jeep Tech -
Category: Jeep
Satisfied Customers: 18958
Experience:  18+yrs experience. State Inspector & Jeep Diagnostics/Repair
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My 1999 Jeep Wrangler is having an issue with the check

Customer Question

My 1999 Jeep Wrangler is having an issue with the check engine light. The code comes up as an evap leak. My mechanic has replaced the leak detection pump and the vent cylinder. Light came back on -- any thoughts?
Submitted: 2 years ago.
Category: Jeep
Expert:  Ron Z. replied 2 years ago.

Do you happen to have the actual "p-code" associated with this?

Customer: replied 2 years ago.
no -- I am always told that it reads a minor gas vapor detection
Expert:  Ron Z. replied 2 years ago.

Ok. Not a problem. If it's "minor EVAP leak" I'm thinking it should be P0442. No problem. First, make sure the replacement fuel cap meets OE specs. Many aftermarket "universal" or "locking" fuel caps will not seal the system and do not meet specs. If you are sure the cap is OE specs, then the next most efficient route here is to have the EVAP System "smoked". This is where a machine forces smoke through the EVAP System and any leaks will reveal themselves. This is good for leaks that may be hard to see by eye, like a vacuum line or the fuel pump seal atop the fuel tank. If the smoke test proves no leaks in the system, then an extremely common fail item on these vehicles that sets a "leak" code is a faulty EVAP Purge Solenoid. The Purge Solenoid is located under the hood, mounted to a bracket right next to the Leak Pump. Inspect the electrical connector and wire harness for any loose, broken or damaged wires. Very carefully inspect all the vacuum lines in this area for any cracks, holes or disconnections. If the visual inspection checks ok, replace the Purge Solenoid. Please remember to leave a rating using the star rating system at the top of this page or accept the answer so I may be credited for this Q&A. You can ask follow-up questions any time, even after you rate or accept.

Expert:  Ron Z. replied 2 years ago.


Expert:  Ron Z. replied 1 year ago.