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Discussion Starter · #1 ·
Will a code PO442 cause the engine to run rough? I got the light first, then a few days latter my car started running rough mostly when its cold. I know this has been coverd a few times on here but I have never seen anyone mentioning that the car was not running right.

Thanks,
Adam
 

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P0442 = small EVAP leak. This will not cause the engine to run rough. Most common cause for 442 is a loose gas cap or the cap gasket has developed small cracks.

I would suspect you have a vacuum leak.
 

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Discussion Starter · #3 ·
Thats what I was afraid of!
 

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Any suggestions on what to look for after replacing the gas cap? Mines got that code also and we've put over 300 miles since that change. The light is still on and it's getting about time for our annual safety inspection and it won't pass with the check engine light on.
 

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Did you reset the code after replacing the cap? EVAP test only runs under a very specific set of conditions, and wont run at all if temps are under 40 deg or so. It also wont run during short trip driving, and under hard acceleration (due to fuel slosh), etc. the CEL wont go off on its own until after the EVAP test has completed at least once.
 

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Discussion Starter · #6 ·
To let you know what happened, the code was caused by the little rubber elbow on the end of the intake that goes down to the PCV valve had cracked. The rough idle was caused by the coil pack going bad. Two easy fixes for once.
 

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^ Might check the condition of the vacuum hose near the green-capped evap. test port on the pass. firewall that goes to the uim (upper intake manifold). After a couple of bends, it will connect to a metal pipe behind the engine.
 

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Did you reset the code after replacing the cap? EVAP test only runs under a very specific set of conditions, and wont run at all if temps are under 40 deg or so. It also wont run during short trip driving, and under hard acceleration (due to fuel slosh), etc. the CEL wont go off on its own until after the EVAP test has completed at least once.
Didn't know I'd have to reset the code. I was told it would reset on it's own after driving a bit. I figured a round trip of over 150 miles each way would have reset it, but if it's got to be above a certain temp, that may be delaying it. I'll look up the reset procedure and try that.

Thanks
 

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Seems like that's all I needed to do. I pulled the battery cables last night, ran some errands, and hooked everything back up. No CEL after that, or today.

Thanks for the help
 

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It may return if you havent really found all the leaks. EVAP IM takes quite a while to complete under typical driving conditions..... often the last IM to complete. Some bidirectional scan tools can force the EVAP test to run so you get imediate results.
 
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