I have 2005 neon sxt keep having code po457 evap emmission loose cap /off replaced cap from chrysler ck eng light comes back on same code anybody have any suggestions

gas cap code p0449 ??? This is not a gas cap code ! DTC P0449: Evaporative Emission (EVAP) Vent Solenoid Control Circuit.. your best bet , take it to a qualified chevy repair shop .


Wells EVAP Training with Sgt Tech P0440 P0441 P0442 etc

457 is loose gas cap
page 9-2 in the service manual.
456 is EVAP leak, small,. saMe loose cap
this is like the #1 failure off every car here from 1996 to now.
loss cap.
reset the DTC using scan tool
put the cap tight, and drive.
if comes back then cap is bad.
if still comes back the tank venting system does leak.
for sure there is a leak only WHAT is not known
in a shop they do leak down test , if pass , the cap was bad. or loose.

Check all hoses and fittings from evap back to fuel tank. On 1post in pacifica world the prob was solved by dropping the fuel tank and replacing the fitting on one of the fuel pumps. Then clear the code and hopefully doesn't come back.

You have an intermittent problem, and it's probably going to be horribly difficult to track down. Your best bet might be to borrow an OBDII scan tool so you can read the codes while the problem is happening.

That mechanic who visually inspected your camshaft position sensor apparently doesn't understand that the sensor can LOOK just FINE while at the same time it's as dead as a doornail. You might try having that one sensor replaced, just to be sure.

Hi there:
DTC P0441 - Evap. Emission System Incorrect Purge Flow
Possible causes: poor/loose connection, faulty purge control solenoid valve (PCSV), faulty PCM.

Check for loose electrical connector and for loose or broke vacuum hose to it. If ok, you will need a voltmeter and vacuum gauge to test it. If fails test, replace it, if ok, then likely a faulty pcm. Most of the time it is either a bad vacuum hose to it or faulty PCSV.

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p0455 is for evap leaks check hose on the passenger side by the fender under the hood a hose coming from the engine to the purge control valve one of the rubber hose is probably broken

Small vacuum leak to start in evap system, which can quite often be traced back to gas cap. I'd clean gas cap seal good & add a little Vaseline, to the rubber "O" ring on cap, and wipe surface where cap screws in real good & clean, then have codes erased, or disconnect battery for a few seconds, and then see if it comes back. Make sure you put cap on tight after adding fuel.

P0457 is a loose gas cap, P0456 is a small evap system leak. The seal on your gas cap is probably worn. Replace the cap, clear the codes with either a diagnostic tester or by disconnecting the battery for a few minutes and reconnecting it. It will take a few days for the code to come back if it isn't fixed, but that usually does the trick. I hope this helps.

On the gas cap itself theres a rubber o-ring.If thats quashed in any way you'll need to replace it.Sometimes takink the o-ring off and putting it back on fixes the problem.Its a very common problem ans is not that expensive to fix..The reason the code keeps coming back is because its a pressurize system and if theres a leak in the system it will throw the light in the dash..

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a small evap leak is often interpreted as a loose gas cap , which it can be , it means the evap systems integrity has been breached , it can be an electrical solenoid , switch or just a vacuum line in the system . a bidirectional scanner can run the evap test after checking the gas cap , most well equipped shops can hook up a smoke machine to the evap system service port and run the smoke test , it there is a leak you will see the smoke , makes the diagnosis quickly . get an estimate from a reputable shop , by the way this problem has no effect on drivability , but should be fixed . cheers