Parts or components should not be replaced with reference to only a P1100 Toyota DTC. The vehicle service manual should be consulted for more information on possible causes of the fault, along with required testing.
Evaporative emissions systems test for a leak in the fuel tank and associated hoses. To perform the test, the computer pulls a vacuum and checks to see if the vacuum holds. Each car maker uses a different techniques to check, but most often it's some type of fuel tank pressure sensor.
P1100 Toyota Possible Solution:
Air Conditioning Pressure Sensor (ACP) Insufficient Pressure Change Each time the A/C clutch engages, the PCM is looking for a pressure change in the refrigerant. If the change in pressure is outside of the calibration the DTC will set. A/C system mechanical failure Open ACP or VREF circuit A/C sensor damaged A/C system electrical failure A/C clutch always engaged Verify A/C system function, including refrigerant charge.