| WARNING | Read service precautions before proceeding with service procedure. See SERVICE PRECAUTIONS . |
| CAUTION | If Engine Control Module (ECM) replacement is instructed in following test, always ensure ECM electrical connectors and ground circuits are okay. If either are defective, repair and repeat testing to confirm ECM malfunction. |
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, canister closed valve Vacuum Switching Valve (VSV) and purge flow switching valve 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. Canister closed valve VSV may also be referred to as CCV VSV. Possible causes are
- Damaged, disconnected or restricted vacuum hose(s) or tubes.
- Fuel tank cap is loose or improperly installed.
- Defective fuel tank cap.
- Damaged fuel tank filler pipe or fuel tank.
- Defective charcoal canister.
- Vapor pressure sensor circuit is open or shorted.
- Defective vapor pressure sensor.
- Defective valves on fuel tank.
- 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. When ENGINE RUN TIME in freeze frame data is less than 200 seconds, check EVAP VSV, charcoal canister and vapor pressure sensor.
Scheme 318
- Check for cracks and deformations in fuel tank, charcoal canister and fuel tank filler pipe. Charcoal canister is located near fuel tank. (Scheme 318) Check for loose connections and disconnected hoses and tubes around fuel tank and charcoal canister. If no problems exist, go to next step. If any problem exists, repair as necessary.
- 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.
- 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.
- 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.
- Visually inspect fuel tank filler pipe for damage. If fuel tank filler pipe is not damaged, go to next step. If fuel tank filler pipe is damaged, replace fuel tank filler pipe.
- Check vapor pressure sensor connection at fuel tank. Vapor pressure sensor is located on corner of fuel tank. (Scheme 318) Check vacuum hoses to charcoal canister, purge flow switching valve VSV and EVAP VSV for correct installation, loose connections, disconnected hoses and damage. (Scheme 318)for component location. If no problems exist, go to next step. If any problem exists, repair or replace components as necessary.
- Check hoses and tubes between fuel tank, fuel tank filler pipe, charcoal canister and fresh air valve for correct installation, loose connections, being disconnected and damage. Fresh air valve is located on top of fuel tank, near end of charcoal canister. (Scheme 318) If no problems exist, go to next step. If any problem exists, repair or replace components as necessary.
- Check charcoal canister for cracks or damage. If charcoal canister is okay, go to next step. If charcoal canister is damaged, replace charcoal canister. See CHARCOAL CANISTER under EMISSION SYSTEMS & SUB-SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION - 4-CYLINDER article.
- Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 3 Turn ignition on. Using voltmeter, check voltage between terminals No. 2 (Yellow/Red wire) and No. 18 (Brown wire) at ECM electrical connector E8. see scheme 7 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.
- Turn ignition off. Connect voltmeter between terminals No. 18 (Brown wire) at ECM electrical connector E8 and No. 22 (Blue/Red wire) at ECM electrical connector E9. see scheme 7 This is the E2 and PTNK terminals on ECM. Remove fuel tank cap. Turn ignition on and note voltage. Voltage should be 3.0-3.6 volts. If voltage is not within specification, go to next step. If voltage is within specification, go to step 12.
- 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. See VAPOR PRESSURE SENSOR under EMISSION SYSTEMS & SUB-SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION - 4-CYLINDER article. If wiring harness or electrical connector is defective, repair as necessary.
- Inspect fuel tank and any valves on fuel tank for cracks and damage. If fuel tank or valves are defective, repair or replace components as necessary. If fuel tank and valves are okay, it is likely that DTC was caused by fuel tank cap not being fully tightened or was improperly installed.