Monday, August 28, 2006

2002 Caravan with codes P0442 and P0456 causing the check engine light to come on


Steady check engine light in the dash panel after engine is started. Codes p0442 and P0456 coming on after being scanned. Checked and tightened up the gas filler cap and reset engine computer but the codes came back.

Basic Concept:

These codes pop up whenever there is a vacuum leak in the evaporative system comprised mainly of the vacuum (charcoal) canister and its solenoids, purge solenoids, vacuum hoses connected to it including the vacuum hose fuel tank connections, vapor separator and the gas cap. Normally, tightening the gas cap will do away with these codes but it seems there are other problem associated with it but the main culprit is the vacuum leak. Pay particular attention to the vacuum canister and its plastic connections that is proned to crack causing the vacuum leak.

Evaporative fuel system is a fuel emission recovey process use to channel fuel vapor from your fuel tank to your engine to get it burnt instead of emitting the fuel vapor to the atmosphere causing pollution.

Repair Strategy:

Do a visual inspection on all connections to the vacuum canister and the vacuum solenoids, vapor separator and all vapor hoses that can cracked over some time. ATS can provide you with the vacuum diagram of the system and if the vacuum leak cannot be found, it is highly recommended to have it "smoked" using a smoking machine that can detect even the smallest vacuum leak. The smoking machine is discussed in ATS or you can contact any garage to do it for you. Once the vacuum leak is found and repaired, reset the code and road test the vehicle to verify the code.


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