This code is a generic
powertrain code. It is considered generic because it applies to all
makes and models of vehicles (1996-newer), although specific repair
steps may vary depending on the model.
The Powertrain Control Module (PCM) / Engine Management Computer (EMC) /
Engine Control Module (ECM) has detected a fault with the circuit that
controls the vent for evaporative emission systems vapor.
As fuel sits in the tank it lets out fuel vapor, while driving this vent
opens and allows the vapors to be circulated into the engine intake
manifold, a charcoal canister or into the atmosphere, depending on the
vehicle. This vent valve is apart of the simple, yet complicated
evaporative emissions system.
Symptoms of a P0449 DTC will include Malfunction Indicator Lamp (MIL)
illumination, you will likely not notice any other symptoms.
Potential causes may include:
Faulty vent valve
Some steps to take to diagnose and repair this trouble code include the
Check your fuses, there may be a fuse that powers the vent solenoid.
Check for a rubbed-through or chafed wiring harness. Check both wires to
see if they are shorted to each other, to ground or power.
Visually inspect the vent valve for cracks or damage.
Trace the wires to and from the PCM/EMC/ECM and check for continuity
continuity using a digital volt ohm meter (DVOM).
If you have access to an advanced level scan tool, actuate the valve
while reading power and ground at the connector or by simply using a
bulb wired to both terminals, it will light up if power and ground are
Using a DVOM, check the resistance of the vent, in most cases the
resistance reading should be low, refer to the manufacturer's
specification or compare it to a new one. Too high or low a value
indicates a faulty coil inside the valve, thusly meaning replacement is
necessary. This code seems to be prevalent on Dodge, Chrsyler, and Jeep
products. In those cases the vent valve was bad. With GM products
(specifically pickups), GM has released a new updated valve assembly.
Finally, remove the valve, you may be able to access the pintle inside
and it simply could just be sticking from fuel residue. Clean it and
Read more at: http://www.obd-codes.com/p0449