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

Is there approx. 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 FTP sensor voltage with the Honda PGM Tester, or measure voltage between PCM connector terminals A29 and C18, and carefully squeeze the vacuum pump slowly.
10. The voltage should smoothly drop from approx. 2.5 V down to approx. 1.5 V. STOP applying vacuum when the voltage drops to approx. 1.5 V or damage to the FTP sensor may occur.

Does the voltage drop to approx. 1.5 V and hold?

YES - Check for misrouted, leaking, or broken FTP sensor vacuum lines. If the vacuum lines are OK, substitute a known-good ECM/PCM and recheck. If the symptom/indication goes away, replace the original ECM/PCM.

NO - Replace the FTP sensor.