Service engine light stays changed gas cap done smoke test replaced oxygen sensor

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

Re: Replacing O2 sensor - Cadillac Forums

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Sorry mate, I dont know what this Gas cap is, could be the fuel filler cap, could be the car runs on LPG and it is a cap on the Gas charge line.

http://www.p0420.com/ explains it could be oxygen sensor or cat

when the car is off it has to vent so you can you can fill the tank a scanner can be used to close the vent valve but for a po443 i would say it is the
purge valve or wireing
with the key on 12 volts must come to the pink wire the solinoid should be about 20 ohms andcheck the comtinuity of green/white wire pin 42 on the ecm

i have got this code before and it just be lose gas cap.....but have also had to replace the cap on a few of them .....the vent hole in it gets cloged....hope it helps

the car is telling you that it is DUE for a service SOON.

The error that I'm showing for error code P1133 is 
P1133 Heated Oxygen Sensor (HO2S) insufficient switching bank 1 sensor 1(Rear Bank).  I would suggest having both of your Oxygen Sensors replaced if you haven't already had that done.  Hope this helps.  Thanks for an honest rating and for using FixYa.

PO135 is oxygen sensor Bank1 sensor1. PO404 is EGR.
personally, I'd pull EGR off, clean pintle good with throttle body cleaner or carb cleaner, re-install, erase codes & try it for a while & see if it code(s) come back.

put a new gas cap, those system are pres. even if
the cap look ok it maby leaking replace with a new
one it should solve your prob.
eng.ligh come on because of the gas cap