2002 Toyota Camry Error code P1451

P1451 - Diagnostic Module Tank Leakage (DM-TL) Switching Solenoid Control Circuit Signal Low

This is not a code I've run into before but it is important to understand that diagnostic fault codes never say to replace parts or that they're defective. They only indicate the circuit or system that needs further diagnosis. A sensor referenced in a code can be defective but that only occurs about half of the time. There could also be a problem with the wiring going to it.

This code description suggests it's related to the system that puts the fuel tank under a small pressure or vacuum, then it is monitored to determine if there is a leak in the vapor recovery system. No one would ever know that unless it was really bad, but those are responsible for a lot of emissions due to fuel vapors escaping, including when the car is standing still. These systems check for those leaks on '96 and newer cars.

If the mechanics are experienced with your car model, they may know a part to be a common cause of this code. Without that experience, the proper procedure is to do some electrical checks first to rule out everything but the sensor.