Question about 1999 Jeep Cherokee
P0442 - Evaporative Emission Control System Leak Detected (small leak)
This indicates a fuel vapor leak in the EVAP control system. It means a very small leak has been detected. In fact, the leak can be from a hole as small as 0.04" in diameter. The (EVAP) emission control system prevents the escape of fuel vapors from a vehicle's fuel system. Fuel vapors are routed by hoses to a charcoal canister for storage. Later, when the engine is running a purge control valve opens allowing intake vacuum to siphon the fuel vapors into the engine.
Symptoms: You likely won't notice any drivability problems.
Causes: A code P0442 most likely means one or more of the following has happened:
* A loose or improperly affixed gas cap
* A non-conforming gas cap (i.e. not factory/original brand)
* A small leak/hole in a fuel vapor hose/tube
* Other small leak in EVAP system
* Faulty vent o-ring seal
Possible Solutions: with a P0442, the most common repair is to:
* Remove and reinstall the gas cap, clear the codes, and drive for a day and see if the codes come back.
* Otherwise, replace the gas cap, or
* Inspect the EVAP system for cuts/holes in tubes/hoses
P0445 - Evaporative Emission Control System Purge Control Valve Circuit Shorted.
Possible Solutions: with a P0445, the most common repair is to:
* Bad or loss contact wires
* Check harnesses, replace it
Hope helps (remember to rate this).
Posted on Nov 05, 2010
I had the same vacuum problem. It took me a whole day to trace out all the vacuum lines that were dry rotted. This two really bad ones were near the driver side of the transmission and also on top of the gas tank near where the fuel pump is. I later talked to a mechanic and told him about my ordeal and he stated Jeeps were known for this.I used a small 8 gallon air tank with a regulator set about 10psi to run air into vacuum lines and you will have to listen very carefully for the hiss. Another pair of ears listening will be handy. (check in quiet place while jeep is not running :) )
Posted on Sep 01, 2010
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