Jetta 2006 Code P0456

456 is a small evap leak check hoses to evap canister by fuel tank.

Code 456 is a common code for a small leak in the evap system. The evap system is how the computer vents gas fumes from the gas tank.
The problem could be a faulty gas cap, the cap left off with the engine running, or something else.

Code 456 means the computer has found a small leak in the EVAP system. The computer vents the gas tank to the vapor canister several times while the engine is running. The system has to be sealed to work properly.
Someone would need to test the venting system for leaks. It could be the gas cap or a valve or hose.

The next step is to get a smoke check which usually tells you where the leak is. Good luck!

What code ? P0442 or P0456 or p0455
DTC EVAP P0442 P0455 P0456
EVAP Leaks P0442 and P0455

Wells EVAP Training with Sgt Tech P0440 P0441 P0442 etc

http://www.obd-codes.com/p0456

This is usually caused by a gas cap that was not put on properly after a fill up. If this is the case then simply tighten the gas cap and the check engine light should go out in a few days with regular driving or reset with a code reader. You may have to replace the gas cap if the code remains. be sure to get the correct cap.

Check the link above for further tests.

P0456 = "Evaporative emission (EVAP) control system leak detected (very small leak)."

P0456 A small Evaporative Emission Control System leak has been detected P0700 Transmission Control System Malfunction P1794 is: Powertrain Control Module Battery Direct Power Circuit

Now, what can we find from all of these.....the first one p0456...mostly refers to improper sealing of the gas cap, so replace this fairly cheap....
now 0700 normally refers to a transmissioin fault..but the third one p1794 refers to battery power...so I would be first checking to see if battery charging system is functioning correctly.....a charging rate at idel should be 13.8-14.4v......as the 0700 code could be related to this issue.....check the transmission fluid.......should be cherry red, not smell burnt or brown.......is this car regularly serviced.......if so, what does the vehilce do that leads you to think there might be a problem....apart from the engine light.....

Lastly, these codes may not be current ones, but maybe you started the car with the gas cap off, for instance and it logged this code..so see if you can clear them, and see what remains behind.

P0456 is Evap Emission control small leak detected.
P0522 Engine oil pressure sensor low voltage.
The first code could be related to a loose, defective, or missing gas cap.
The second code, could be a defective sensor but you will need to confirm. Check oil level and condition first then onto the sensor and related wiring.

P0456 = EVAP Emissions Control System Leak Very Small

Is the gas cap on tight or is the seal damaged? If it needs replacement, get it from the dealer.