P0451

DTC P0451: FTP Sensor Range/Performance Problem

Special Tools Required
Vacuum Pump/Gauge, 0 - 30 in. Hg A973X-041-XXXXX

1. Remove the fuel fill cap.
2. Turn the ignition switch ON (II).




3. Monitor the fuel tank pressure (FTP) sensor voltage with the Honda PGM Tester, or measure voltage between ECM/PCM connector terminals E4 and E14.

Is there about 2.5 V?

YES - Go to step 4.

NO - Replace the FTP sensor. 4. Turn the ignition switch OFF.

5. Disconnect the hose between the EVAP two way valve and the FTP sensor at the EVAP two way valve end.




6. Connect a vacuum pump to the open end of that hose.
7. Turn the ignition switch ON (II).




8. Monitor the FTP sensor voltage with the Honda PGM Tester, or measure voltage between ECM/PCM connector terminals E4 and E14, and slowly squeeze the vacuum pump.
9. The voltage should drop smoothly from about 2.5 V down to about 1.5 V. STOP applying vacuum when the voltage drops to about 1.5 V or damage to the FTP sensor may occur.

Does the voltage drop to about 1.5 V and hold?

YES - Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck. If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.

NO - Replace the FTP sensor.