Circuit Description

Fuel tank pressure sensor is mounted to sending unit at top of fuel tank. Sensor measures pressure changes within EVAP system. Sensor has a 5 volt reference, a ground and a signal circuit.

Sensor contains a diaphragm which changes resistance based on pressure. When EVAP system pressure is low (during purge), sensor output voltage is low. When EVAP system pressure is high, sensor output voltage is high. When ECM senses sensor signal voltage outside normal operating range of sensor, this DTC will set.

Conditions required to set DTC are:

• Tank pressure is more or less than 1.1 in. H2O for at least 5 seconds.
• Tank pressure is greater than 0.4 H2O for at least 3 seconds.