They have to do with the evaporative control system. Start by checking the gas cap (tight, no dirt or obstructions). Failing that, there is probably a leak somewhere in the fuel system somewhere.
I believe it has a computer connection, so take it to your nearest Auto Zone, the will hook it uo the their computer for free. Or call the Dodge dealer and ask
SOURCE: Error codes P0442 and P0455 in Dodge Dakota 2001
Hello shoretex...Yes sir you can repair this yourself...
p0442 is medium leak detected ...p0456 is small leak....and p0440 is a general evap system failure.. evap codes are a common thing. gas caps are an inexpensive place to start. There are two types of evap hoses on the Dodge... hard plastic and soft rubber.... before you replace parts check the soft rubber first at the evap cans and pump located about a foot in front of the gas tank fill pipe on trucks located next to the transfer case or right behind the trans on the driver side. hard plastic lines will brake or rub through...check spots where lines come in contact with anything. this is a common thing with older trucks...hair line cracks will kick a p0442 code, and a p0445 code...When you find a leak, repair it, and rescan...sometimes there are several leaks, continue with inspection and repairs until you get it all fixed up.... Remember..start at simple and work from there...
i will post the evap. system in more detail to help you troubleshoot the problem.
EVAP System:
The Evaporative Emission (EVAP) Control system used on all vehicles is the charcoal canister storage method. This method transfers fuel vapor from the fuel tank to an activated carbon (charcoal) storage device (canister) to hold the vapors when the vehicle is not operating. When the engine is operating, the fuel vapor is purged from the carbon element by intake air flow and consumed in the normal combustion process.
The evaporative system includes the following components:
*Fuel tank
*Evaporative emission canister vent solenoid
*Fuel tank pressure sensor
*Fuel pipes and hoses
*Vapor lines
*Fuel cap
*Evaporative emission canister
*Purge lines
*Purge valve solenoid
EVAP System Operation:
The EVAP purge solenoid valve allows manifold vacuum to purge the canister. The Powertrain Control Module (PCM) supplies a ground to energize the EVAP purge solenoid valve (purge on). The EVAP purge solenoid control is Pulse Width Modulated (PWM) or turned on and off several times a second.
The EVAP canister purge PWM duty cycle varies according to the operating conditions determined by the mass air flow, the fuel trim, the engine coolant temperature, and the intake air temperature. For certain EVAP tests, the diagnostic will be disabled if the TP angle increases to above 75% .
The evaporative leak detection diagnostic strategy is based on applying vacuum to the EVAP system and monitoring for vacuum decay.
The fuel level sensor input to the PCM is used to determine if the fuel level in the tank is correct to run the EVAP diagnostic tests. To ensure sufficient volume in the tank to begin the various diagnostic tests, the fuel level must be between 15% and 85% .
The PCM monitors the fuel tank pressure/vacuum level via the fuel tank pressure sensor input.
Results of Incorrect Operation:
Poor idle, stalling and poor driveability can be caused by the following:
*Malfunctioning purge solenoid.
*Damaged canister.
*Hoses/lines split, cracked and/or not connected properly.
Evidence of fuel loss or fuel vapor odor can be caused by the following:
*Liquid fuel leaking from the fuel lines
*Cracked or damaged canister
*Inoperative canister control valve
Vacuum hoses that are:
*Disconnected
*Mis-routed
*Kinked
*Deteriorated
*Damaged
The evaporative leak detection diagnostic strategy is based on applying vacuum to the EVAP system and monitoring vacuum decay.
The PCM monitors vacuum level via the fuel tank pressure sensor input. At an appropriate time, the EVAP purge solenoid and the EVAP vent solenoid are turned on, allowing engine vacuum to draw a small vacuum on the entire evaporative emission system. After the desired vacuum level has been achieved, the EVAP purge solenoid is turned off, sealing the system. A leak is detected by monitoring for a decrease in vacuum level over a given time period, all other variables remaining constant. A small leak in the system causes DTC P0442 to be set.
If the desired vacuum level cannot be achieved in the test described above, a large leak or a faulty EVAP purge solenoid is indicated. This can be caused by the following conditions:
*Disconnected or faulty fuel tank pressure sensor.
*Missing or faulty fuel cap.
*Disconnected, damaged, pinched, or blocked EVAP purge line.
*Disconnected or damaged EVAP vent hose.
*Disconnected, damaged, pinched, or blocked fuel tank vapor line.
*Disconnected or faulty EVAP canister solenoid.
*Disconnected or faulty EVAP vent solenoid.
*Open ignition feed circuit to the EVAP vent or purge solenoid.
*Damaged EVAP canister.
Any of the above conditions sets DTC P0440. A restricted or blocked EVAP canister vent path is detected by drawing vacuum into the EVAP system. The PCM turns off the EVAP vent solenoid and the EVAP purge solenoid (EVAP vent solenoid Open, EVAP purge PWM 0% ). The PCM monitors the fuel tank pressure sensor input. With the EVAP vent solenoid open, any vacuum in the system should decrease quickly unless the vent is blocked. A blockage is caused by the following conditions:
*Faulty EVAP vent solenoid (stuck closed).
*Plugged, kinked, or pinched vent hose.
*Shorted EVAP vent solenoid driver circuit.
*Plugged evaporative canister.
Good luck shoretex, hope this helps...please take time to rate me a fixya.
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