P1450

Symptoms

• Check engine light
• hard starting or long crank times
• classically right after refueling (car cranks but won't start, or starts and immediately stalls)
• poor fuel efficiency
• excessive vacuum can in severe cases collapse the fuel tank and damage the fuel pump and fuel level sender.

Probable causes

1) Stuck-open EVAP purge valve — engine vacuum is continuously applied to the EVAP system and tank ('suction that won't stop'). 2) Blocked EVAP canister or canister vent solenoid preventing the tank from venting. 3) Kinked or collapsed hose between the canister and the fuel tank. 4) Faulty fuel tank pressure (FTP) sensor.

Diagnostic steps

1. Scan codes and record freeze frame data; note whether the fault set after refueling.
2. With a scan tool, monitor the fuel tank pressure sensor with the engine running: it should read near zero at idle — a pressure reading dropping significantly into vacuum as the engine runs is the definitive confirmation of P1450.
3. Test the purge valve: verify it is not stuck open (it should hold closed with no command); a stuck-open purge valve floods the intake with rich vapors after refueling and pulls constant vacuum on the tank.
4. Inspect the hoses between the fuel tank, canister and vent for kinks, collapse or blockage.
5. Check the EVAP canister and vent solenoid for blockage and verify the vent flows freely.
6. Use a smoke machine or soapy water solution to check the EVAP plumbing for restrictions/leaks as needed.
7. Replace the faulty component (purge valve, vent solenoid, canister, hose or FTP sensor), clear codes, and verify tank pressure stays near zero on a drive cycle including a refuel test.