Evaporative Emission (EVAP) System Malfunction

EVAPORATIVE EMISSION (EVAP) SYSTEM MALFUNCTION DETECTION CONDITIONS AND POSSIBLE CAUSES

DTC P0455, P0456, P01443	EVAPORATIVE EMISSION (EVAP) SYSTEM MALFUNCTION
DETECTION CONDITION	P0455 indicates a substantial leak or blockage has been detected in the EVAP system when there is -1.74 kPa (-7.0 in-H₂ O) or less vacuum for 30 seconds evaluation time. P0456 indicates a fuel vapor leak from an opening as small as 0.506 mm (0.020 inch) is detected by the EVAP running loss monitor test. P1443 indicates a substantial leak and no purge flow has been detected in the EVAP system when there is -1.74 kPa (-7.0 in-H₂ O) or less vacuum for 30 seconds evaluation time with less than 0.02 lb/min vapor flow.
POSSIBLE CAUSE	Aftermarket EVAP hardware (such as fuel filler cap) non-conforming to required specifications (P0455) Disconnected or cracked fuel EVAP canister tube, EVAP canister purge outlet tube or EVAP return tube (P0455) EVAP canister purge valve stuck closed (P0455) Damaged or missing fuel filler cap (P0455) Insufficient fuel filler cap installation (P0455) Loose fuel vapor hose/tube connections to EVAP system components (P0455) Blockages or restrictions in fuel vapor hoses/tubes (P0455) Fuel vapor control valve tube assembly or fuel vapor vent valve assembly blocked (P0455) Canister vent (CV) solenoid stuck open (P0455) Mechanically inoperative fuel tank pressure (FTP) sensor (P0455) Very small holes or cuts in the fuel vapor hoses/tubes (P0456) Loose fuel vapor hose/tube connections to the EVAP system components (P0456) EVAP system component seals leaking (see Possible Cause under DTC P0442) (P0456) Pinched, blocked or plugged fuel vapor tubes/hoses except between fuel tank and EVAP canister (P1443) Damaged EVAP canister (P0455, P1443) Disconnected, cracked or cut fuel vapor tubes/hoses except between fuel tank and EVAP canister (P1443) Damaged EVAP canister purge valve (P1443)
HINT	See EVAP vapor management flow system monitor or EVAP running loss system monitor. See EVAPORATIVE EMISSION (EVAP) MONITOR AND SYSTEM MALFUNCTION .

EVAPORATIVE EMISSION (EVAP) SYSTEM MALFUNCTION DIAGNOSTIC PROCEDURE

DTC P0455, P01443		EVAPORATIVE EMISSION (EVAP) SYSTEM MALFUNCTION
STEP	INSPECTION		ACTION
1	Was the PCM quick test performed?	Yes	For DTC P0455: Go to next step. For DTC P1443: Go to step 3.
1	Was the PCM quick test performed?	No	Perform PCM quick test. See PCM QUICK TEST .
2	VISUALLY CHECK FOR LARGE EVAP SYSTEM LEAK Check for the presence of a fuel filler cap. DO NOT tighten or check for correct installation at this time. Verify that both the input port vacuum hose and EVAP return tube are attached to the EVAP canister purge valve. Verify that the canister vent solenoid is properly attached to the EVAP canister. Visually inspect for disconnected or cracked fuel vapor hoses/tubes between the intake manifold and the following components: EVAP canister purge valve EVAP canister Fuel vapor vent valve assembly Check for damage to the fuel filler pipe and the fuel tank. Is a concern visually evident?	Yes	Repair or install new EVAP components as necessary. See FUEL FILLER PIPE REMOVAL / INSTALLATION See CANISTER VENT SOLENOID REMOVAL / INSTALLATION . See EVAPORATIVE EMISSIONS VALVE REMOVAL / INSTALLATION . See CANISTER PURGE VALVE REMOVAL / INSTALLATION . Go to step 7.
2		No	Go to next step.
3	CHECK FOR EVAP SYSTEM LEAKS Disconnect the EVAP return tube from the intake manifold and plug the EVAP return tube. Connect the EVAP system leak tester to the EVAP test port. Perform the EVAP system leak test. See EVAPORATIVE EMISSION SYSTEM LEAK TEST . Does the pressure stay above 1.99 kPa (8 in-H ₂ O)?	Yes	Go to next step.
3		No	Verify that the fuel filler cap is installed correctly. Repair or install new components as necessary. Go to step 7.
4	CHECK FOR BLOCKAGE BETWEEN THE EVAP CANISTER PURGE VALVE AND THE CANISTER VENT SOLENOID NOTE: The EVAPCV will automatically cancel after 9-minutes of continuous operation. Key ON, Engine OFF (KOEO). Using IDS or equivalent tester, select Diagnostic Data Link. Select PCM. Select Active Command Modes. Select Output Test Mode. Close EVAP Canister Vent (CV) solenoid using EVAPCV PID. Pressurize the EVAP system to 3.48 kPa (14 in-H₂ O). Press STOP (#4) to open the CV solenoid. Does the pressure drop immediately?	Yes	Go to next step.
4		No	Install a new vapor line between the EVAP canister purge valve and the fuel vapor tee located on the frame rail near the rear of the fuel tank. Go to step 8.
5	CHECK FOR BLOCKAGE BETWEEN FUEL FILLER PIPE AND THE FUEL VAPOR TEE NOTE: The EVAPCV will automatically cancel after 9 minutes of continuous operation. Connect the EVAP system leak tester to the fuel filler pipe. Using IDS or equivalent tester, select Diagnostic Data Link. Select PCM. Select Active Command Modes. Select Output Test Mode. Close EVAP Canister Vent (CV) solenoid using EVAPCV PID. Pressurize the EVAP system to 3.48 kPa (4 in-H₂ O). Press STOP (#4) to open the CV solenoid. Does the pressure drop immediately?	Yes	Go to next step.
5		No	Install new fuel tank vapor line(s). Repeat this step to verify repair. Go to step 8.
6	CHECK FOR FAILED EVAP CANISTER PURGE VALVE OR FUEL TANK PRESSURE SENSOR Were both P0455 and P1443 present at step 1?	Yes	Install a new EVAP canister purge valve. See EVAPORATIVE EMISSIONS CANISTER REMOVAL / INSTALLATION . Go to next step.
6		No	Install a new fuel tank pressure sensor. See FUEL TANK PRESSURE SENSOR REMOVAL / INSTALLATION . Go to next step.
7	EVAP SYSTEM LEAK TEST Connect all disconnected connectors and hoses. Perform the EVAP system leak test. See EVAPORATIVE EMISSION SYSTEM LEAK TEST . Is test result OK?	Yes	Go to step 9.
7		No	Leakage still exists. Locate leak point and repair. Repeat this step.
8	DRIVE CYCLE Connect all disconnected connectors. Clear DTCs from PCM memory using IDS or equivalent tester. Perform EVAP System Monitor Drive Cycle. See DRIVE CYCLES . Retrieve pending code. Is same DTC present?	Yes	Replace PCM. See POWERTRAIN CONTROL MODULE (PCM) REMOVAL / INSTALLATION . Go to next step.
8		No	Go to next step.
9	VERIFY REPAIR Perform PCM quick test. Is any DTC present?	Yes	Go to applicable DTC inspection. See DIAGNOSTIC TROUBLE CODE (DTC) INDEX - POWERTRAIN CONTROL MODULE (PCM) .
9	VERIFY REPAIR Perform PCM quick test. Is any DTC present?	No	Troubleshooting is complete.

EVAPORATIVE EMISSION (EVAP) SYSTEM MALFUNCTION DETECTION CONDITIONS AND POSSIBLE CAUSES

DTC P0457	EVAPORATIVE EMISSION (EVAP) SYSTEM MALFUNCTION
DETECTION CONDITION	P0457 indicates the initial vacuum could not be achieved after a refueling event and the purge vapor flow is excessive (gross leak).
POSSIBLE CAUSE	Missing or loose fuel filler cap
HINT	Fuel Filler Cap Description Used to prevent fuel spillage and close the evaporative emission/fuel system to atmosphere.

EVAPORATIVE EMISSION (EVAP) SYSTEM MALFUNCTION DIAGNOSTIC PROCEDURE

DTC P0457		EVAPORATIVE EMISSION (EVAP) SYSTEM MALFUNCTION
STEP	INSPECTION		ACTION
1	Was the PCM quick test performed?	Yes	Go to next step.
1	Was the PCM quick test performed?	No	Perform PCM quick test. See PCM QUICK TEST .
2	CHECK FOR MISSING OR LEAKING FUEL FILLER CAP Check for missing or loose fuel filler cap. Check for possible cross-threaded fuel filler cap. Is a concern present?	Yes	Repair or replace as necessary. Go to next step.
2		No	Go to step 4.
3	EVAP SYSTEM LEAK TEST Perform the EVAP system leak test. See EVAPORATIVE EMISSION SYSTEM LEAK TEST . Is test result OK?	Yes	Go to step 5.
3		No	Leakage still exists. Go to P0455 Troubleshooting. See EVAPORATIVE EMISSION (EVAP) SYSTEM MALFUNCTION .
4	DRIVE CYCLE Connect all disconnected connectors. Clear DTCs from PCM memory IDS or equivalent tester. Perform EVAP system monitor drive cycle. See DRIVE CYCLES . Retrieve pending code. Is DTC P0455 and P0457 still present?	Yes	Go to P0455 Troubleshooting. See EVAPORATIVE EMISSION (EVAP) SYSTEM MALFUNCTION .
4		No	Go to next step.
5	VERIFY REPAIR Perform PCM quick test. Is any DTC present?	Yes	Go to applicable DTC inspection. See DIAGNOSTIC TROUBLE CODE (DTC) INDEX - POWERTRAIN CONTROL MODULE (PCM) .
5	VERIFY REPAIR Perform PCM quick test. Is any DTC present?	No	Troubleshooting is complete. Advise customer that it is important and necessary to tighten the fuel filler cap after refueling.