P0448: Evaporative Emission Control System Vent Valve/Solenoid Circuit Shorted

What Does The P0448 Code Mean?

The Powertrain Control Module (PCM) has detected that the circuit is shorted together that controls the vent valve or solenoid for evaporative emission systems vapor. In this case the code will also be thrown when the valve is stuck closed.

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.

What Are The Symptoms Of The P0448 Code?

Symptoms of a P0448 DTC will include Malfunction Indicator Lamp (MIL) illumination, you will likely not notice any other symptoms.

What Are The Potential Causes Of The P0448 Code?

Potential causes may include:

• Faulty vent valve
• Wire/circuit issue
• PCM fault

How Can You Fix The P0448 Code?

Some steps to take to diagnose and repair this trouble code include the following:

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 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 OK.

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 retest.

Other EVAP DTCs: P0440– P0441– P0442– P0443– P0444– P0445– P0446– P0447– P0449– P0452– P0453– P0455– P0456

Recommended Parts

Below are some recommended auto parts to help you address the trouble code affecting your vehicle and get it running smoothly again:

>>> WORKPRO 582-piece Crimp Terminals, Wire Connectors, Heat Shrink Tube, Electrical Repair Kit
>>> ECU
>>> INNOVA 5210
>>> KAIWEETS Digital Multimeter

Note: During the purchasing process, please check carefully whether the part you want to buy fits your car!

Check This Video For Reference

Reference Sources

ENGINE CONTROL SYSTEM [GASOLINE ENGINE (V-6)] SERVICE MANUAL for P0448 – Pages 565-568.