P0456 - Evaporative Emissions System - Small leak detected - Dodge Truck

What does that mean?

The Powertrain Control Module (PCM) at different times performs various tests on the EVAP system. OBD II Enhanced EVAP systems are in place to keep fuel tank vapors from venting into the atmosphere, and instead purges them into the engine to be burned. Regular pressure tests are conducted by the PCM to monitor the sealed system for leaks. The PCM monitors the EVAP system pressure by watching the fuel tank pressure (FTP) sensor. When the sensor indicates a small leak in the EVAP system, this code is set.

Potential Symptoms

There will likely be no noticeable symptoms other than the Malfunction Indicator Lamp (MIL). This is because the EVAP system is a closed system and only controls fuel tank vapors, not engine management.

Causes

Usually this P0456 code is caused by an incorrect or faulty gas cap. Filling the fuel tank with the engine running could conceivable cause this code as well or if the cap wasn't properly tightened. Any of the following could also be the cause:

• A small leak in any of the EVAP hoses or fuel tank hoses
• A small leak in the purge valve or vent valve
• The EVAP Canister may be leaking

Possible Solutions

First, using a scan tool activate the vent solenoid, sealing the system. Then monitor the fuel tank pressure (FTP) sensor. If the system is sealing properly, the number will stay consistent. If is isn't, the pressure sensor will show that as well. If the system slowly leaks, use a smoke machine and watch for smoke exiting the system at any EVAP component. Any where there is smoke exiting the system, that is the faulty component. Do not pressurize the EVAP system with air pressure. Doing so can damage the purge and vent solenoids in the system.

• Step 1 of 3
  Connect the scan tool to the Ford's diagnostic port, located next to the steering column under the driver's side of the dashboard. The port will have a small cover over it with the letters "DTC" embossed on the face of the cover. Pull that cover off to access the port. You can purchase a scan tool at your neighborhood auto parts store. Make sure the scan tool you are interested in buying works with Ford vehicles.
•  Step 2 of 3
  Run a self test on the system by following the directions in your scan tools specific owner's manual. When the codes are read, make sure the P0456 is the only code present before erasing the codes. If another code is present, you will need to have it diagnosed and corrected before you clear the codes.
•  Step 3 of 3
  Erase the code when prompted to do so by the scan tool. Complete the self test and disconnect the scan tool. Replace the diagnostic port cover.

Tips & Warnings

• If you pull a P0456 when reading codes, the first thing you should do is make sure your gas cap is on securely. If it isn't, tighten it down properly and clear the code out. If the light returns within the next hundred miles of driving, you should have the code diagnosed by a certified driveability technician.
• Never leave your engine running when filling your tank. This can cause the power train control module to assume it is detecting any of several malfunctions due to the lost pressure in the fuel vapor system and the upward mobility of the fuel level sensor.
• Additionally, never top off the gas tank after the station's pump clicks off. The additional gas you pump in can flow into the evaporative fuel system and cause damage which will cost you far more than the price of a tank of gasoline to repair.