Sfi System - P0441

1. Dtc summary

2. Description

3. Monitor description

4. Monitor strategy

5. Typical enabling conditions

6. Typical malfunction thresholds

7. Monitor result

8. Inspection procedure

DTC P0441 Evaporative Emission Control System Incorrect Purge Flow

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DTC SUMMARY

DESCRIPTION

MONITOR DESCRIPTION

1. Key-off monitor
   5 hours* after the ignition switch is turned OFF, the leak detection pump creates negative pressure(vacuum) in the EVAP system. The ECM monitors for leaks and actuator malfunctions based on the EVAP pressure.
   

   HINT:

   *: If the engine coolant temperature is not below 35°C (95°F) 5 hours after the ignition switch is turned OFF, the monitor check starts 2 hours later. If it is still not below 35°C (95°F) 7 hours after the ignition switch is turned OFF, the monitor check starts 2.5 hours later.

   
   

   Sequence	Operations	Descriptions	Duration
   -	ECM activation	Activated by soak timer 5, 7 or 9.5 hours after ignition switch OFF.	-
   A	Atmospheric pressure measurement	Vent valve turned OFF (vent) and EVAP system pressure measured by ECM in order to register atmospheric pressure. If pressure in EVAP system not between 70 kPa and 110 kPa (525 mmHg and 825 mmHg), ECM cancels EVAP system monitor.	10 seconds
   B	First 0.02 inch leak criterion (reference pressure) measurement	In order to determine 0.02 inch leak criterion, leak detection pump creates negative pressure (vacuum) through reference orifice and then ECM checks if leak detection pump and vent valve operate normally.	60 seconds
   C	EVAP system pressure measurement	Vent valve turned ON (closed) to shut EVAP system. Negative pressure (vacuum) created in EVAP system, and EVAP system pressure then measured. Write down measured value as it will be used in leak check. If EVAP pressure does not stabilize within 900 seconds, ECM cancels EVAP system monitor.	900 seconds*
   D	Purge VSV monitor	Purge VSV opened and then EVAP system pressure measured by ECM. Large increase indicates normal.	10 seconds
   E	Second 0.02 inch leak criterion (reference pressure) measurement	After second 0.02 inch leak criterion measurement, leak check performed by comparing first and second 0.02 inch leak criterion. If stabilized system pressure higher than second 0.02 inch leak criterion, ECM determines that EVAP system leaking.	60 seconds
   F	Final check	Atmospheric pressure measured and then monitoring result recorded by ECM.	-

   *: If only a small amount of fuel is in the fuel tank, it takes longer for the EVAP pressure to stabilize.
   
   
   
   
   
   
2. 1. Purge VSV stuck open
      In operation C, the leak detection pump creates negative pressure (vacuum) in the EVAP system. The EVAP system pressure is then measured by the ECM using the canister pressure sensor. If the stabilized system pressure is higher than [second 0.02 inch leak criterion x 0.2], the ECM interprets this as the purge Vacuum Switching Valve (VSV) being stuck open. The ECM illuminates the MIL and sets the DTC (2 trip detection logic).
      
      
      
      
      
      
   2. Purge VSV stuck closed
      In operation D, the canister pressure sensor measures the EVAP system pressure. The pressure measurement for the purge VSV monitor begins when the purge VSV is turned ON (open) after the EVAP leak check. When the measured pressure indicates an increase of 0.3 kPa (2.25 mmHg) or more, the purge VSV is functioning normally. If the pressure does not increase, the ECM interprets this as the purge VSV being stuck closed. The ECM illuminates the MIL and sets the DTC (2 trip detection logic).
      
      
      
      
      
      
3. Purge flow monitor
   The purge flow monitor consists of the 2 step monitors. The 1st monitor is conducted every time and the 2nd monitor is activated if necessary.
   

1. The 1st monitor
   While the engine is running and the purge VSV is ON (open), the ECM monitors the purge flow by measuring the EVAP pressure change. If negative pressure is not created, the ECM begins the 2nd monitor.
   
2. The 2nd monitor
   The vent valve is turned ON (closed) and the EVAP pressure is then measured. If the variation in the pressure is less than 0.5 kPa (3.75 mmHg), the ECM interprets this as the purge VSV being stuck closed, and illuminates the MIL and sets DTC P0441 (2 trip detection logic).
   

MONITOR STRATEGY

TYPICAL ENABLING CONDITIONS

1. 
   

   1. Atmospheric pressure measurement

   Next sequence is run if the following condition is set	-
   Atmospheric pressure	Within 0.3 kPa (2.25 mmHg) in 1 second

   
   

   2. First reference pressure measurement

   Next sequence is run if the following conditions are set	-
   EVAP pressure just after reference pressure measurement start	-1 kPa (-7.5 mmHg) or less
   Reference pressure	-4.85 to -1.057 kPa (-36.38 to -7.93 mmHg)
   Reference pressure	Saturated

   
   

   3. EVAP canister vent valve close stuck check

   Next sequence is run if the following condition is set	-
   EVAP pressure change after vent valve is ON	0.3 kPa (2.25 mmHg) or more

   
   

   4. Vacuum introduction

   Next sequence is run if the following condition is set	-
   EVAP pressure	Saturated within 15 minutes

   
   

   5. EVAP canister purge valve close stuck check

   Next sequence is run if the following condition is set	-
   EVAP pressure change after purge valve is open	0.3 kPa (2.25 mmHg) or more

   
   

   6. Second reference pressure measurement

   Next sequence is run if the following conditions are set	-
   EVAP pressure just after reference pressure	-1 kPa (-7.5 mmHg) or less
   Reference pressure	-4.85 to -1.057 kPa (-36.38 to -7.93 mmHg)
   Reference pressure	Saturated
   Difference between the first reference pressure and the second reference pressure	Less than 0.7 kPa (5.25 mmHg)

   
   

   7. Leak check

   Next sequence is run if the following condition is set	-
   EVAP pressure when vacuum introduction is complete	Lower than second reference pressure

   
   

   8. Atmospheric pressure measurement

   EVAP monitor is complete if the following condition is set	-
   Atmospheric pressure difference between sequence 1 to 8	Within 0.3 kPa (2.25 mmHg)

TYPICAL MALFUNCTION THRESHOLDS

MONITOR RESULT

INSPECTION PROCEDURE