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DTC codes / Subaru codes / P1144

P1144 · SubaruPressure Sensor Circuit High Input

P1144 on a Subaru indicates that the engine control module (ECM) has detected an abnormally high voltage signal from a pressure sensor circuit, typically the fuel tank pressure sensor used for evaporative emissions monitoring. The ECM expects the sensor's output to stay within a specific voltage range, and a high input means the signal wire is seeing voltage above the normal threshold, which can be caused by a short to voltage, a faulty sensor, or a wiring issue.

SystemPowertrain
Code typeSubaru specific
SeverityMedium
Fix difficultyIntermediate
AreaFuel and air metering

Symptoms you may notice

  • Illumination of the check engine light, often with no other noticeable symptoms.
  • Slight fuel odor or hissing from the fuel tank area if the pressure sensor is stuck high and affects evap system operation.
  • Failed emissions test due to the check engine light being on.
  • In rare cases, rough idle or driveability issues if the high input is caused by a short that affects shared sensor reference voltage.
  • Intermittent warning light if the fault is due to a loose connection or chafed wire.

Common causes, most likely first

  1. Faulty fuel tank pressure sensor sending an abnormally high voltage signal.
  2. Short to voltage on the signal wire between the pressure sensor and the ECM.
  3. Damaged or corroded electrical connector at the pressure sensor or ECM.
  4. Open ground circuit for the pressure sensor, causing the signal to float high.
  5. Failed ECM driver or internal fault in the pressure sensor circuit (rare).
  6. Aftermarket or incorrect pressure sensor installed that does not match Subaru specifications.
  7. Wiring harness damage from rodents, road debris, or improper previous repairs.

How to diagnose and fix it

  1. Connect a scan tool and verify the P1144 code is current, then check live data for the fuel tank pressure sensor voltage to confirm it is abnormally high.
  2. Visually inspect the pressure sensor connector and wiring for corrosion, loose pins, or chafing, and repair as needed.
  3. Disconnect the sensor and measure reference voltage and ground at the connector with a multimeter; compare to Subaru service specifications.
  4. Check for a short to voltage on the signal wire by measuring voltage with the sensor disconnected and the key on; repair any short.
  5. Test the pressure sensor itself by applying vacuum or pressure and monitoring the signal voltage; replace if it does not respond correctly.
  6. If wiring and sensor test good, check continuity and resistance of the ground circuit back to the ECM, repairing any open or high-resistance ground.
  7. Clear the code and perform a drive cycle to verify the repair; if the code returns, consult Subaru service information for ECM diagnostics.

What Subaru Techs Check First for P1144

  • A common oversight is assuming the fuel tank pressure sensor is bad when the real problem is a chafed signal wire shorting to a nearby power wire in the harness near the fuel tank.
  • On some Subaru models, the fuel tank pressure sensor is part of the evap canister assembly and cannot be replaced separately, so technicians must test the circuit thoroughly before condemning the entire assembly.
  • A high input code can be set by a poor ground connection at the sensor, which causes the signal voltage to rise; always verify ground integrity before replacing parts.
  • The ECM may set P1144 intermittently if the sensor connector is not fully seated after previous evap system repairs, so check for recent service history.
  • Do not confuse P1144 with other pressure sensor codes; Subaru uses similar codes for different sensors, so confirm the exact circuit and sensor location in the service manual.

Can I keep driving with P1144?

You can generally continue driving with P1144 because it primarily affects the evaporative emissions system and does not usually cause drivability problems, but avoid ignoring it if you notice a fuel smell or other symptoms. Have the vehicle diagnosed soon to prevent potential emissions test failure and to rule out a more serious electrical short.

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.

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