Faulty fuel tank pressure sensor giving an inaccurate reading; Sticking or failed fuel tank pressure control solenoid valve; Leaking or disconnected EVAP hose between the tank and the purge or vent valve; Loose, damaged, or missing fuel filler cap; Cracked or damaged fuel tank or filler neck; Failed canister purge valve or charcoal canister that cannot hold pressure; Wiring or connector issue at the fuel tank pressure sensor or control solenoid

DTC codes / Subaru codes / P1401

P1401 · SubaruFuel Tank Pressure Control System Performance

Q: What does code P1401 mean?

Fuel Tank Pressure Control System Performance. P1401 on a Subaru means the engine control module (ECM) has detected a performance problem with the fuel tank pressure control system, which is the evaporative emission (EVAP) system's ability to hold and release fuel vapor pressure as designed. The ECM typically runs a self-test that pressurizes or monitors the tank and expects a certain pressure change within a set time, and this code sets when that change does not occur or the system cannot maintain the expected pressure.

P1401 on a Subaru means the engine control module (ECM) has detected a performance problem with the fuel tank pressure control system, which is the evaporative emission (EVAP) system's ability to hold and release fuel vapor pressure as designed. The ECM typically runs a self-test that pressurizes or monitors the tank and expects a certain pressure change within a set time, and this code sets when that change does not occur or the system cannot maintain the expected pressure.

SystemPowertrain

Code typeSubaru specific

SeverityLow

Fix difficultyIntermediate

AreaAuxiliary emission controls

Symptoms you may notice

Illuminated check engine light, often with no other noticeable symptoms
A slight fuel odor around the rear of the vehicle after refueling
Difficulty or hesitation when refueling, such as the pump clicking off early
Rough idle or slight hesitation that may come and go
In rare cases, a hiss or whoosh when removing the fuel cap

Common causes, most likely first

Faulty fuel tank pressure sensor giving an inaccurate reading
Sticking or failed fuel tank pressure control solenoid valve
Leaking or disconnected EVAP hose between the tank and the purge or vent valve
Loose, damaged, or missing fuel filler cap
Cracked or damaged fuel tank or filler neck
Failed canister purge valve or charcoal canister that cannot hold pressure
Wiring or connector issue at the fuel tank pressure sensor or control solenoid

How to diagnose and fix it

Inspect the fuel filler cap for a tight seal and correct installation, and replace it if the gasket is cracked or missing
Visually check all EVAP hoses and connections at the tank, canister, and purge valve for cracks, looseness, or disconnection
Use a scan tool to command the fuel tank pressure control solenoid and observe the fuel tank pressure sensor reading for proper response
Perform a smoke test on the EVAP system to locate any leaks that are not visible
Test the fuel tank pressure sensor with a multimeter or scan tool to confirm it reports pressure changes accurately
Check the control solenoid and purge valve for mechanical function and electrical resistance, replacing if out of specification
Inspect the wiring and connectors at the fuel tank pressure sensor and control solenoid for corrosion or damage, and repair as needed

What the P1401 test actually checks

The ECM often runs the fuel tank pressure control test only under specific conditions such as a cold start or after a certain fuel level, so the code may not set every drive cycle.
A fuel tank pressure sensor that reads slightly off can cause this code without any visible leak, making sensor testing more important than a quick visual inspection.
Subaru EVAP systems can be sensitive to aftermarket fuel caps that do not seal correctly, so always use a genuine or OEM-equivalent cap.
The code can be set by a sticking fuel tank pressure control solenoid that fails to vent or seal when commanded, even though the solenoid coil tests good with a multimeter.
A smoke test is the most reliable way to find small leaks that do not produce a visible fuel smell or drip.

Can I keep driving with P1401?

You can usually continue driving with P1401 because it is an emissions-related fault and does not affect engine safety, but avoid topping off the fuel tank and have the system checked soon to prevent a small leak from worsening.

Tools that help

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Guidance is general and written for Subaru vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.