Evaporative Emission System Pressure Sensor/Switch

What it means

The engine computer (ECU) has detected an electrical problem in the fuel tank pressure (FTP) sensor circuit. The fuel tank pressure (FTP) sensor measures pressure and vacuum in the fuel tank and EVAP system so the ECU can test for fuel vapour leaks. The signal is missing or outside the range the ECU will accept.

Symptoms

• Check engine light on
• Usually no driving symptoms
• Other EVAP codes may set
• Fails emissions inspection

Probable causes

Most likely first

1. 1Damaged, corroded or unplugged connector
2. 2Open or shorted signal, reference or ground wire
3. 3Failed sensor
4. 4ECU fault (rare)

How to diagnose it

Work through these in order before buying parts

1. 1Record the code and its freeze frame data (speed, load, temperature when it set), then clear it and see if it comes back.
2. 2Inspect the fuel tank pressure (FTP) sensor connector and wiring (on top of the fuel tank, on the fuel pump module, or near the charcoal canister). Look for corrosion, bent or pushed-back pins, oil contamination and chafed insulation.
3. 3Watch the fuel tank pressure (FTP) sensor reading on live data. With the fuel cap removed it should read close to 0 (atmospheric pressure). Replace the cap and the reading should change slightly as the fuel warms.
4. 4With the key on and the sensor unplugged, check for about 5 volts on the reference wire and a good ground (under 0.1 V drop) on the ground wire. Back-probe the signal wire with the sensor connected and watch the voltage change smoothly.
5. 5If the wiring checks out, test the sensor itself against the specification in a service manual.
6. 6Check for technical service bulletins (TSBs) or software updates for your make and model; some codes have known factory fixes.

Common fixes

• Repair the damaged wiring or connector
• Replace the fuel tank pressure (FTP) sensor
• Clear the code and test drive to confirm the repair