My 2004 Jeep Liberty 3.7 Liter V6 engine light came on. Codes P0440 and P0441. All emissions related. I don't think its the gas cap. How do I determine which component/part is messed up without spending "an arm and a leg"?
P0440 Evaporative Emission Control System Malfunction
P0441 Evaporative Emission Control System Incorrect Purge Flow
Leaks in the system have their own dedicated fault codes. They can usually be found with a "smoke machine". These codes suggest fuel vapors aren't being removed from the charcoal canister to be burned in the engine. Unfortunately we aren't to the point where fault codes say to replace a part. That is never the case. They only tell you the circuit or system that needs further diagnosis. You can do a visual inspection of hoses, parts and wiring but a scanner is typically needed to turn valves on and off to see if they respond, and to view live data to see how the sensors are responding.