The code p0440 check engine light is i have 100000 miles car

It might be open door?

Disconnect the negative battery cable for 30 minutes. Reconnect after and the code will clear. However if the problem persists, the code will come back with in 20 miles or 30 minutes.

here's your code. P0440 OBD II Trouble Code

The error code p0420 does not rise only due to faulty catalytic converter but may also rise due to one of following reason:

1. Faulty rear O2 sensor

2. Damaged O2 sensor wiring

3. Exhaust leak

The error code p0401 indicates faulty Engine Gas Recirculation (EGR) valve. The remedy to the problem is:

a. Replace EGR valve

b. Repair damaged wiring of EGR valve

c. Clean the EGR valve tubing

PO 440 is an EVAP System issue,not specific

Have that system checked out

Probably can't hurt. The 300 code is ignition system/misfire. And the 440 code has to do with emissions. The misfire condition is probably causing a sensor to pick up a problem with your emissions

yes it would be a smart thing to do and no it is not that hard it should onlt have two bolts holding it on

wow thermostat >>>> shucks i believe its evep emissions code like faulty gas cap ....you can reset any computer the chck eng light will come on in 50 to 100 miles if not fixed....

i have 2003 trailblazer ltz 153 000 mileage i have code po440 .i changed gas cap and turned off the chech engine light... i made 300 miles and it was good and today morning i drove a mile and light turned on ..... what do i have to fix ...thanks

check our automatic idle sensor some times refered to as a air intake sensor, also your throtle body sensor, while doing these 2 things remove the 4 bolts holding your throtle body inplace carefully remove it, and clean it all out with carb cleaner. I believe between these simple steps your problem will go away. the other thing to check being that you have 100000 miles is your o2 sensors, you probably have 2 of them. You can not fix them, once they are dead they are dead, and they tipicaly last right around 100000 miles.

tepfy