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Home >> Mazda >> 2002 >> Tribute LX, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 27 (Engine Controls - Self-Diagnostics - 2.5L) >> Diagnostic Tests >> DTC P0446: EVAP Control System Vent Control Malfunction >> Diagnosis & Repair Procedure

Diagnosis & Repair Procedure

WARNING: This page is about a different car, the 2002 Mazda 626. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ensure FREEZE FRAME DATA has been recorded. Check for related service bulletins. Repair as necessary and go to next step.
  2. Turn ignition on. Using scan tool, check FTP V PID data. Start engine and allow it to idle for 3 minutes. Loosen fuel cap. If FTP V PID is 2.42-2.58 volts, secure fuel cap and go to step  4 . If FTP V PID is not 2.42-2.58 volts, secure fuel cap and go to next step.
  3. Turn ignition off. Disconnect FTP sensor connector. Turn ignition on. Measure voltage between FTP sensor harness connector Gray/Red wire terminal and ground. If 4.5-5.5 volts is present, replace FTP sensor and go to step  12 . If 4.5-5.5 volts is not present, repair open in circuit. See WIRING DIAGRAMS article. Go to step  12 .
  4. Check fuel vapor hoses for kinks between fuel tank and in-line tee, and between in-line tee, purge solenoid valve and charcoal canister. Disconnect both ends of fuel vapor hose between charcoal canister and pressure control valve. Using vacuum pump ensure fuel vapor hose does not hold vacuum. Check for excessive debris between charcoal canister atmosphere venting port and CDCV. Check for kinks in purge air inlet tube between CDCV and atmosphere. Repair as necessary and go to step  12 . If no problem is found, go to next step.
  5. Remove vent hose from CDCV. Inspect and ensure air flows through hose. If vent hose is okay, go to step  8 . If air does not flow through vent hose, go to next step.
  6. Remove check valve from CDCV vent hose. Ensure check valve is not blocked. Replace as necessary and go to step  12 . If check valve is okay, go to next step.
  7. Remove air filter from CDCV vent hose. Ensure air filter is not blocked. Replace as necessary and go to step  12 . If air filter is okay, check CDCV vent hose for other damage. Replace as necessary and go to step  12 .
  8. Turn ignition off. Disconnect hoses from CDCV. If CDCV is directly connected to charcoal canister, disconnect fuel vapor hose located between purge solenoid valve and charcoal canister at canister. Install vacuum pump to vent port of CDCV. Disconnect CDCV connector. Connect battery voltage and ground to CDCV connector terminals. Apply 16 in. Hg to CDCV. If vacuum is held for one minute, replace CDCV and go to step  12 . If vacuum is not held for one minute, go to next step.
  9. Check CDCV operation. See SYSTEM & COMPONENT TESTING - MIATA, MILLENIA, MPV, PROTEGE, PROTEGE5 & 626 article. Replace CDCV as necessary and go to step  12 . If CDCV is okay, go to next step.
  10. Turn ignition off. Disconnect PCM connector. Inspect connector for loose, damaged or corroded terminals. Measure resistance between PCM harness connector terminal No. 18 (Light Green wire) and No. 51 (Black/Blue wire), and between terminal No. 18 (Light Green wire) and No. 103 (Black/Red wire). See Figure . If resistance is 10 k/ohms or less, repair short to ground in appropriate wire. See WIRING DIAGRAMS article. Go to step  12 . If resistance is greater than 10 k/ohms, go to next step.
  11. Inspect fuel tank for any indication of leaking or cracks. Replace as necessary and go to next step. If fuel tank is okay, symptom may be caused by a fuel filling shut off problem. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article.
  12. Reconnect all connections. Turn ignition on. Clear DTCs. See CLEARING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. Start engine. Using scan tool, perform OBD II drive mode. See DRIVE MODES  under SELF-DIAGNOSTIC SYSTEM. Using scan tool, access DIAGNOSIS MONITORING TEST RESULTS. Monitor TEST #10:26:00 (EVAP phase 0), #10:27:00 (EVAP phase 2), and #10:2A:00 (EVAP vapor gen). If measured value is within specification, replace PCM and go to next step. See REMOVAL, OVERHAUL & INSTALLATION article. On vehicles equipped with immobilizer system, reprogram ignition key identification numbers. See COMPUTER RELEARN PROCEDURES - IMPORT article in GENERAL INFORMATION. If measured value is not within specification, go to next step.
  13. Perform DTC confirmation procedure. See DTC CONFIRMATION PROCEDURE  under SELF-DIAGNOSTIC SYSTEM. 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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