Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC P0451: Fuel Tank Pressure Sensor Circuit Range/Performance Problem
2004 Acura 3.5RLSECTION DTC P0451: Fuel Tank Pressure Sensor Circuit Range/Performance Problem
WARNING: This page is about a different car, the 2003 Acura RSX. However, it is still accessible from the selected car via links, so may be relevant.
- Perform ECM/PCM reset procedure. See ECM/PCM RESET PROCEDURE/CLEARING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM. Remove fuel filler cap. Turn ignition switch on. Using scan tool, monitor Fuel Tank Pressure (FTP) sensor voltage or measure voltage between White ECM/PCM 31-pin "E" harness connector terminals No. 4 (Pink wire) and 14 (Light Green wire). If about 2.5 volts are present, go to next step. If about 2.5 volts are not present, check vacuum lines for restriction or blockage. Repair as necessary. If vacuum lines are okay, replace fuel tank pressure sensor.
- Disconnect hose to FTP sensor from EVAP 2-way valve end. Connect vacuum pump to open end of disconnected hose. Turn ignition switch on. Using scan tool, monitor FTP sensor voltage or measure voltage between White ECM/PCM 31-pin "E" harness connector terminals No. 4 (Pink wire) and 14 (Light Green wire). See Figure . Using vacuum pump, apply vacuum slowly. Voltage should smoothly drop from about 2.5 volts to about 1.5 volts. If voltage drops from about 2.5 volts down to about 1.5 volts, update ECM/PCM or substitute with known-good ECM/PCM. If symptom or indication goes away, replace original ECM/PCM. If FTP sensor voltage does not drop as specified, replace FTP sensor.
CAUTION:
Stop applying vacuum when voltage drops to about 1.5 volts. Damage to fuel tank pressure sensor may occur.
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.