What does it mean?
The OBDII system on 1996 and newer vehicles is equipped with an evaporative emissions monitor that performs diagnostic self-checks to detect fuel vapor leaks. If a leak is detected, then a code is set in the engine control module and the check engine light is illuminated. The component that reads the fuel vapor pressure is the evaporative emission control system pressure sensor, also referred to as the fuel tank pressure sensor.
The evaporative emission (EVAP) control system pressure sensor is used for onboard diagnosis of the EVAP system itself to check for leaks and does not initiate or control changes to the EVAP purge or vent valve operations. It detects and measures pressure in the purge line of the EVAP system. The pressure sensor’s output voltage increases as the pressure in the purge line increases, and the sensor voltage output is monitored by the engine control module (ECM).
The EVAP system pressure sensor is located at the EVAP canister. It can be mounted directly on the canister or it may be connected to the EVAP canister by a section of hose. EVAP control system pressure sensor. The EVAP control system pressure sensor converts pressure to a voltage reading. The sensor voltage is then communicated to the ECM via a signal wire connected to the sensor. There are three wires for the EVAP pressure sensor: a ground, a 5v reference signal, and the sensor signal wire.
The EVAP pressure sensor is only monitored under certain conditions which can make it tricky to diagnose. Voltage is monitored by the ECM only once the vehicle speed sensor has recorded a trip of one minute at a minimum speed of 10 miles per hour. The ECM only monitors the EVAP control system pressure sensor when the fuel tank level is between 25 and 75 percent. The code P0452 is set when the ECM reads a low voltage signal from the EVAP control system pressure sensor.
Note: Circuit Low Input codes are often the result of low battery voltages (that can have many possible causes), bad connections across electrical connectors or previously repaired wiring, as well as corrosion in electrical connectors.
Other possible causes of low input voltages include poor installation of aftermarket components, poor quality aftermarket components like fuses, relays, and switches, and modification of the electrical system that could include the use of conductors that are not rated for use in a particular application. However, poor connections often result in high resistances in some parts of the circuit, which is why it is important to perform resistance and continuity checks during the diagnostic procedure.