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Home >> Mazda >> 2001 >> MX-5 Miata Base, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0451: Fuel Tank Pressure Sensor, Performance Problem >> Diagnosis & Repair Procedure

Diagnosis & Repair Procedure

  1. Ensure FREEZE FRAME DATA has been recorded. Check for related service bulletins. Repair as necessary and go to next step.
  2. Turn ignition off and on. Using scan tool, check for DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. If DTCs P0443 or P1449 are present, diagnose and repair these DTCs first. If DTCs P0443 and P1449 are not present, go to next step.
  3. Disconnect purge solenoid valve hoses. Connect vacuum pump to purge solenoid valve. Apply vacuum. Turn ignition on. Using scan tool, access SIMULATION TEST and turn CDCV PID on. If purge solenoid valve releases vacuum, go to next step. If purge solenoid valve does not release vacuum, replace purge solenoid valve and go to step  7.
  4. Disconnect CDCV hoses. Connect vacuum pump to CDCV and apply vacuum. Turn ignition on. Using scan tool, access SIMULATION TEST and turn CDCV PID on. If CDCV holds vacuum for 3 seconds, go to next step. If CDCV does not hold vacuum for 3 seconds, replace CDCV and go to step  7.
  5. Turn ignition off. Remove charcoal canister located beside fuel tank. Inspect for charcoal canister for plugging. If charcoal canister is okay, go to next step. If charcoal canister is plugged, replace canister and go to step  7.
  6. Inspect Fuel Tank Pressure (FTP) sensor. See SYSTEM & COMPONENT TESTING - MIATA, MILLENIA, MPV, PROTEGE & 626 article. If FTP sensor is okay, go to next step. If FTP sensor is faulty, replace as necessary and go to step  7.
  7. Ensure fuel tank is 1/4-3/4 full. Using scan tool, monitor PID data for BARO, ECT, IAT and FTL V PID data should read BARO V is 21.3 in. Hg or more, ECT is 14-90.5° F (-10-32.5°C), IAT is 14-140°F (-10-60°C) and FTL V is .24-2.0 volts. If any signals are not within specification, allow engine to cool down and repeat this step. If all signals are within specification, go to next step.
  8. Reconnect all connectors. Perform EVAP monitor repair verification drive mode. See DRIVE MODES  under SELF-DIAGNOSTIC SYSTEM. Access ON BOARD SYSTEM READINESS TEST menu of GENERIC OBD II FUNCTION and check DRIVE MODE completion status. If evaporative purge system monitor is complete, go to next step. If evaporative purge system monitor is not complete, repeat step  7.
  9. Reconnect all connectors. Clear DTCs. See CLEARING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. Turn ignition off. Start engine. Using scan tool, ensure FTP V PID is .2-4.8 volts. Check for DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. If DTC P0451 is present, replace PCM and go to next step. On vehicles equipped with immobilizer system, reprogram ignition key identification numbers. See COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION. If DTC P0451 is not present, go to next step.
  10. Cycle ignition from off to on. Check for DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. If any other DTC is present, go to appropriate test.
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