It told me this:
The computer notices the canister is empty when it detects a leaner condition (all the vapors are used up) and it resumes normal fuel delivery. Some car manufacturers then close the vent solenoid but leave the purge solenoid open. That creates a vacuum throughout the entire fuel storage system. Once the correct vacuum is reached, it closed the purge solenoid and waits to see if the vacuum holds.
then it says how to fix it
The sensors receive a 5 volt reference signal from the PCM. As pressure readings change, the sensor varies the voltage and the computer reads that to determine input. In the case of a broken wire, the sensor never sees the voltage and the computer assumes a major fault. So if you get this P2520 Mercedes-Benz code, first check to make sure you're getting a good 5 volt reference signal at the sensor.
The scent may P2520 Mercedes-Benz signal oil or coolant leaking from their normally closed-loop systems, or it may indicate dangerous exhaust gases invading your car's interior. Car and truck exhaust contains toxic gases such P04B6, so if the inside of your car P04B6 DTC For Ambassador Custom as if you were standing behind your car, get out and get it fixed. Fight the urge to take a little nap first. So sleepy. That's the carbon monoxide talking, friends. At least open a window on your way to the shop.