P1441
Circuit Description
The PCM tests the EVAP system for the following conditions:
^ Large and small leaks (P0440 and P0442)
^ Excess vacuum (P0446)
^ Purge flow during non-commanded conditions (P1441)
^ Fuel Tank Pressure sensor and Fuel Level sensor faults (P0452, P0453, P0462 and P0463) EVAP Purge and Vent Valve faults (P0443 and P0449)
The PCM monitors the amount of vacuum in the EVAP system by monitoring the Fuel Tank Pressure sensor. For this DTC the PCM turns OFF the EVAP Purge Valve and turns ON the EVAP Vent Valve when the Conditions for Running the DTC have been met. This test indicates a leaking EVAP Purge Valve or Flow During Non-Purge if the Fuel Tank Pressure sensor indicates increasing fuel tank vacuum. This DTC will set after two consecutive failures of the above test.
Conditions for Running the DTC
^ No misfire, fuel trim, injector control circuit, AIR, EGR, VSS, HO2S, TP, MAP, MAF, ECT or IAT DTCs set.
^ Battery voltage is between 5 and 18 volts.
^ Barometric pressure is more than 75 kPa.
^ Fuel level is between 15% and 85% of full capacity for at least 10 seconds continuously. The time limit is required because fuel sloshing within the tank may cause the fuel level indication to vary outside the fuel level limits.
^ ECT at start up was between 4°C and 30°C (40°F and 86°F).
^ IAT at start up was between 4°C and 30°C (40°F and 86°F).
^ ECT not more than 8°C above or 2°C below IAT at start up.
Conditions for Setting the DTC
An increasing vacuum in the EVAP system is monitored.
Action Taken When the DTC Sets
^ The PCM illuminates the Malfunction Indicator Lamp on the second consecutive ignition cycle that the diagnostic runs and fails.
^ The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure records.
Conditions for Clearing the MIL/DTC
^ The PCM turns the MIL Off after three consecutive drive trips that the diagnostic runs and does not fail.
^ A last test failed (current DTC) clears when the diagnostic runs and does not fail.
^ A History DTC clears after forty consecutive warm-up cycles, if this or any Other emission related diagnostic does not report any failures.
^ Use a scan tool in order to clear the MIL/DTC.
^ Interrupting the PCM battery voltage may or may not clear DTCs. This practice is not recommended.
Diagnostic Aids
Notice: Use the Connector Test Adapter kit J 35616-A for any test that requires probing the following items:
^ The PCM harness connectors
^ The electrical center fuse/relay cavities
^ The component terminals
^ The component harness connector
Using this kit will prevent damage caused by the improper probing of connector terminals.
Important: An accurate indication of fuel level is required for the PCM to properly Pass or Fail this DTC. Always diagnose fuel level sensor DTCs before performing this DTC's diagnostic table. Always check for fuel level sensor DTCs stored as History.
Perform a physical inspection of the EVAP system. Check for the following conditions:
^ Incorrectly routed or defective EVAP system vacuum and vapor lines.
^ A stuck open EVAP Purge Valve.
^ A malfunctioning or damaged vapor canister
Check for charcoal release from the vapor canister.
The vacuum and pressure in the EVAP system is measured in inches of H2O (water). Most gauges measure vacuum in inches of Hg (mercury) and pressure in psi (pounds per square inch). The following shows how the values compare:
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
3. This DTC should only set if an increasing vacuum was monitored by the PCM while the EVAP Vent and Purge Valves were both sealed.
Check for possible carbon contamination of the EVAP Purge Solenoid Valve and the purge line.