DTC P0440: EVAPORATIVE EMISSION CONTROL SYSTEM Toyota Tundra I

Note. This DTC may be caused by a loose or improperly installed fuel tank cap. If DTC P0441, P0446, P0450 or P0451 is output after DTC P0440, perform appropriate test for these DTCs first before performing test for DTC P0440.

Circuit Description

Vapor pressure sensor and vapor pressure sensor Vacuum Switching Valve (VSV) are used to detect abnormalities in the EVAP system. DTC is set if a leak is detected in EVAP system or vapor pressure sensor malfunctions. Possible causes are

1. Damaged, disconnected or restricted vacuum hose(s) or tubes.
2. Fuel tank cap is loose or improperly installed.
3. Defective fuel tank cap.
4. Damaged fuel tank.
5. Defective charcoal canister.
6. Vapor pressure sensor circuit is open or shorted.
7. Defective vapor pressure sensor.
8. Defective ECM.

Diagnostic Aids

Verify with customer if fuel tank cap has been left off or not completely tightened recently. This may cause DTC to be set. Using Toyota hand-held tester or scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.

Scheme 285

1. Check for any signs of hoses near fuel tank and charcoal canister for modification and for signs of an accident which may have damaged the fuel tank, charcoal canister and fuel inlet pipe which is located between fuel tank and fuel tank cap. Charcoal canister is at driver's side of engine compartment. (Scheme 285) If no problems exist, go to next step. If any problems exists, repair or replace components as necessary.
2. Check fuel tank cap to ensure fuel tank cap is a Original Equipment Manufacturer (OEM) fuel tank cap. If fuel tank cap is an OEM fuel tank cap, go to next step. If fuel tank cap is not an OEM fuel tank cap, replace fuel tank cap with an OEM fuel tank cap.
3. Ensure fuel tank cap is properly installed and tightened. If fuel cap is properly installed and tightened, go to next step. If fuel cap is not properly installed or tightened, reinstall and tighten as necessary.
4. Check fuel tank cap for damage and damaged gasket. If fuel tank cap is not damaged and gasket is okay, go to next step. If fuel tank cap or gasket is damaged, replace fuel tank cap with an OEM fuel tank cap.
5. Visually inspect fuel inlet pipe for damage. If fuel inlet pipe is not damaged, go to next step. If fuel inlet pipe is damaged, replace fuel inlet pipe.
6. Check vacuum hoses to vapor pressure sensor, vapor pressure sensor Vacuum Switching Valve (VSV) and charcoal canister and for correct installation, loose connections, disconnected hoses and damage. (Scheme 285) If no problems exist, go to next step. If any problem exists, repair or replace components as necessary.
7. Check hoses and tubes between fuel tank and charcoal canister for correct installation, loose connections, being disconnected and damage. If no problems exist, go to next step. If any problem exists, repair or replace components as necessary.
8. Check charcoal canister for cracks or damage. If charcoal canister is okay, go to next step. If charcoal canister is cracked or damaged, replace charcoal canister.
9. Remove glove box and heater duct (if necessary) for access to ECM with electrical connectors still installed on ECM. see scheme 2 Turn ignition on. Using voltmeter, check voltage between terminals No. 2 (Green/Black wire) and No. 18 (Green/White wire) at ECM electrical connector E6 with all electrical connectors installed on ECM. see scheme 4 This is the VC and E2 terminals on ECM. Voltage should be 4.5-5.5 volts. If voltage is within specification, go to next step. If voltage is not within specification, replace ECM.
10. Turn ignition off. Connect voltmeter between terminals No. 18 (Green/White wire) at ECM electrical connector E6 and No. 22 (Red/Green wire) at ECM electrical connector E4 and with all electrical connectors installed on ECM. see scheme 4 This is the E2 and PTNK terminals on ECM. Disconnect vacuum hose from vapor pressure sensor. (Scheme 285) Connect hand-held vacuum pump to vacuum hose fitting on vapor pressure sensor. Turn ignition on and note voltage reading with no vacuum applied on vapor pressure sensor. Using vacuum pump, apply 1.18 in. Hg of vacuum to vapor pressure sensor and note voltage reading. Voltage should be 2.9-3.7 volts without vacuum applied and.5 volt or less with vacuum applied. If voltage is not within specification, go to next step. If voltage is within specification, go to step 12.
11. Check for open and short in wiring harness and electrical connectors between vapor pressure sensor and ECM. See WIRING DIAGRAMS article. If wiring harness and electrical connectors are okay, replace vapor pressure sensor. If wiring harness or electrical connector is defective, repair as necessary.
12. Disconnect vacuum hose at charcoal canister that goes back to the fuel tank. Ensure fuel tank cap is properly installed. Apply.7 psi (.05 kg/cm 2 ) air pressure to vacuum hose that goes back to the fuel tank to check fuel tank for leaks. Check that the pressure is maintained after one minute. If the pressure can be maintained, it is likely that DTC was caused by fuel tank cap not being fully tightened or was improperly installed. If pressure cannot be maintained, replace fuel tank.