DTC P0451: Fuel Tank Pressure (Ftp) Sensor Circuit Range/Performance Problem
- Perform PCM reset procedure. See POWERTRAIN CONTROL MODULE RESET PROCEDURE . Remove fuel filler cap. Turn ignition on. Using scan tool, check FTP sensor voltage or backprobe between PCM connector "A" (32-pin connector) terminal No. 29 (Light Green wire) and PCM connector "C" (31-pin connector) terminal No. 18 (Green/Black wire). See Figure and Figure
. If about 2.5 volts exist, go to next step. If about 2.5 volts do not exist, check appropriate vacuum lines for restriction or blockage. Repair as necessary. If vacuum lines are okay, replace FTP sensor.
- Disconnect vacuum hose located between EVAP 2-way valve and FTP sensor at EVAP 2-way valve side. Connect vacuum pump to open end of disconnected hose. See Fig 1. Turn ignition on. Monitor FTP sensor voltage with scan tool, or backprobe between PCM connector "A" (32-pin connector) terminal No. 29 (Light Green wire) and PCM connector "C" (31-pin connector) terminal No. 18 (Green/Black wire) while carefully applying a small amount of vacuum to hose, one stroke at a time. Voltage should drop smoothly from about 2.5 volts to about 1.5 volts. DO NOT apply vacuum after voltage drops to 1.5 volts or damage to FTP sensor may occur. Go to next step.
- If voltage does not drop to about 1.5 volts and hold, replace FTP sensor. If voltage drops to about 1.5 and holds, problem is intermittent. System is okay at this time. Check for poor connections or loose wires at FTP sensor and fuel tank. Perform final procedure. See FINAL PROCEDURE .
Courtesy of AMERICAN HONDA MOTOR CO., INC.