1999 pontiac sunfire code p0440

pressure test radiator by colour check system ,or check for petrol vapour in header tank or radiator, check oil in engine to see if it is contaminated with water oil ,could be leaking rocker cover gasket causeing plugs to missfire if gas, petrol smell from water its head gasket ,water in oil headgasket, oil in water headgaskget if any of these requires head skim and head pressure test by a engineer

There has been a service bulletin isued for that code. I have run into this before, also the wires comming out of the connector. That would bethe first thing to check. Here is what the bulletin states. Emissions - SES Lamp ON/DTC P0440 (EVAP) SetNotesFile In Section: 06 - Engine/Propulsion SystemBulletin No.: 02-06-04-044Date: August, 2002TECHNICALSubject: Service Engine Soon (SES) Light Illuminated, DTC P0440 Set (Replace Fuel Tank Evaporative Emissions Control System (EVAP) Vent Solenoid Harness) Models: 2000-2002 Chevrolet Cavalier2000-2002 Pontiac Sunfire ConditionSome customers may comment that the SES light is/was illuminated.A technician may find DTC P0440 is stored in the PCM.CauseThe EVAP solenoid harness may be misrouted around the rear antilock brake (ABS) wire harness causing a chaff/damage to the EVAP vent solenoid harness, setting DTC P0440.CorrectionFollow the service procedure below to diagnose and correct this condition.1. Install a Tech 2 scan tool and select the appropriate vehicle. Verify that a DTC P0440 is stored in the PCM. 2. Raise the vehicle on a hoist. Refer to Lifting and Jacking the Vehicle in General Information (SI Document ID # XXXXX).



Locate and inspect the EVAP vent solenoid harness (3) routing. The harness may be routed below the ABS wiring harness (4) at the right rear corner of the fuel tank, causing stress on the EVAP solenoid harness (3).





4.Disconnect the EVAP vent solenoid harness (3) from the EVAP vent solenoid (2) and connector C313 (1). Discard the EVAP vent solenoid harness (3).

5.Connect the new EVAP vent solenoid harness (3), P/N 22687059, to the EVAP vent solenoid (2), route the harness above the rear ABS harness (4) and connect the EVAP vent solenoid harness (3) to connector C313 (1).

6.Lower the vehicle.

7.Clear the DTC's with the Tech 2 scan tool.

If all of the wires are good you will want to check for any leaks in the evap system.

Hope helps.

When the light is on you need to pull the OBD codes with a code reader or go to an autopart store and have them do it. With that in mind ethanol changes the exhaust coming out of the engine, the ethanol causes the oxygen to be higher in the exhaust than is expected and the light comes on. You should have the codes checked to be sure. However there is no damage coming from this light, if that is the cause.

I would say start by replacing the gas cap with a genuine GM product. If that doesn't fix it there are a few more suggestions here --> P0440 @ OBD-Codes.com

Take the gas cap off and put it back on then clear the code. This happens some times when the gas cap is put on wrong or not put on at all.

P0442 Evaporative Emission Control System Leak Detected (small leak)
P0440 Evaporative Emission Control System Malfunction

its a small evap leak, could be gas cap, or filler neck, or ring at top of fuel tank to secure the pump. if you are in a rusty area, the necks are bad about a hole rusting in them.

Check your engine coolant.

its your o2 sensor (replace both) about 300-400

if it is a zero tolerance engine there is the possibilty valve damage has occured, depends if you were driving the car and at what speed it happened