What causes code PO440 on 2002 firebird?

Answer 1

I found that the check engine light came on and with a code reader I read a PO440 which says "emissions controls system malfunction". I cleared the code and found that when I tried to get it inspected they said other things were not ready...ie-oxgen sensor, catalytic converter and emissions. They also said that you will have to drive for 100 or so miles to let the ECM register readings again. I kept clearing PO440 code but within 70-80 miles it would return. Same error code PO440. I was told by a mechanic that the evaporator cannister and valve was bad and it will have to be replaced. The labor alone would be over 700.00, the tank would have to be reomved and this was a very laborious job. I decided to go another route. I know I needed to get to the top of the tank. I began removing the carpet from the back of the firebird just in front of the trunk. I used a hacksaw and drill to get at the top left of the gas tank. I used a drill and moved very slowly, not to create any sparks, this was used to make sure I wasn't near any fuel lines. I then used a fine bladed hacksaw and cut into this area until I exposed the cannister. You will have to bend away the sheet metal, be careful the tin is very sharp. Once you have the cannister exposed, you will have to remove the electrical connector and the main hose clamp. Then pry off the hose and remove and replace the cannister. The cannister with electronic valve was 30.00 at GM dealer. I then cleared the code and drove for around 70-80 miles and then took it to be inspected.....it passed this time. By the way, the car was also running much smoother, idling better etc. There is another valve in front by the motor sitting on top of the intake, which I had already replaced earlier. It is easier to get to and it is just the electronic valve. This initially didn't solve the problem, which led me to believe it was the other one on top of the tank. This all ended up costing me 121.00 labor and a few cuts. 30.00 for cannister, 30.00 for the other purge control valve and a 4X4 door on my gas tank which I repaired with a piece of cardboard and duc tape. this was covered up by the carpet once all was finished.