logo
Add Vehicle

EVAP Fuel Tank Pressure Sensor Test

Fuel Tank Pressure Sensor Operation

The Fuel Tank Pressure (FTP) sensor monitors the pressure/vacuum in the EVAP system. The EVAP system relies on this sensor for leak and component testing. It is a 3-wire sensor that has a 5-volt reference circuit, ground circuit and signal circuit. As the pressure/vacuum changes in the system, the sensor reacts and changes the voltage on the signal circuit supplied to the engine control module

Fuel Tank Pressure Sensor Test

illustration of pressure sensor pin out
  1. Check sensor inputs
  • Unplug sensor connector and turn the key-on with the engine off, check for a good 5-volt reference and ground on the appropriate connector pins.
testing sensor with multi meter
Tip : Check service information or contact GoTech techline for pinout information
  1. Check sensor output
  • With sensor plugged in, turn the key on and engine off, using a full functional scan tool check the FTP sensor voltage for correct reading at atmospheric pressure. (See pressure reference chart)
  • If a scan tool is unavailable back probe the signal wire and use a multimeter to read sensor output voltage
  • While monitoring FTP sensor voltage activate purge solenoid with a scan tool or jumper wire and check for a small change(50-500mv) in the signal. This will test the sensor's ability to change voltage and confirm it is not stuck.
testing sensor with multi meter
Tip : Due to some systems design to hold a slight amount of pressure or vacuum it may be necessary to remove the gas cap to equalize pressure before taking reading