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 3.2TL and 2003 Acura 3.2CL. However, it is still accessible from the selected car via links, so may be relevant.
- Remove fuel filler cap. Turn ignition switch on. Monitor Fuel Tank Pressure (FTP) sensor voltage with scan tool or measure voltage (backprobe) between PCM 31-pin "C" harness connector terminal No. 18 (Green/Yellow wire) and PCM 32-pin "A" harness connector terminal No. 29 (Light Green wire - A/T) or PCM 31-pin "A" harness connector terminal No. 28 (Green/Yellow wire) and PCM 31-pin "E" harness connector terminal No. 28 (Light Green wire - M/T). See Figure or Figure . See appropriate wiring diagram under ENGINE PERFORMANCE in WIRING DIAGRAMS. If about 2.5 volts are present, go to next step. If about 2.5 volts are not present, replace FTP sensor.
- Turn ignition switch off. Open fuel vent assembly cover in front of EVAP canister. See Fig 1
. Disconnect vacuum hose between EVAP 2-way valve and FTP sensor at EVAP 2-way valve. Connect vacuum pump to open end of disconnected hose.CAUTION: Damage to fuel tank pressure sensor may occur if vacuum is applied after voltage drops to 1.5 volts.
- Turn ignition switch on. Measure voltage between PCM 31-pin "C" harness connector terminal No. 18 (Green/Yellow wire) and PCM 32-pin "A" harness connector terminal No. 29 (Light Green wire - A/T) or PCM 31-pin "A" harness connector terminal No. 28 (Green/Yellow wire) and PCM 31-pin "E" harness connector terminal No. 28 (Light Green wire - M/T). Carefully pump vacuum one stroke at a time. Voltage should drop smoothly from about 2.5 volts down to about 1.5 volts. If voltage drops to about 1.5 volts and holds, substitute known-good PCM, then recheck. If symptom or indication goes away, replace original PCM. If voltage does not drop to about 1.5 volts and hold, replace FTP sensor.
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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.