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 FTP sensor voltage with the Honda PGM Tester, or measure voltage between PCM connector terminals A29 and C18.

Is there about 2.5 V?

YES - Go to step 4.

NO - Replace the FTP sensor.

4. Turn the ignition switch OFF.




5. Open the fuel vent assembly cover (A) in front of the EVAP canister.
6. Disconnect the hose between the EVAP two way valve and the FTP sensor at the EVAP two way valve end.




7. Connect a vacuum pump to the open end of that hose.
8. Turn the ignition switch ON (II).
9. Monitor the FTP sensor voltage with the Honda PGM Tester, or measure voltage between PCM connector terminals A29 and C18, and slowly squeeze the vacuum pump a little while watching the voltage.
10. The voltage should smoothly drop 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 - Substitute a known-good PCM and recheck. If the symptom/indication goes away, replace the original PCM.

NO - Replace the FTP sensor.