P0442

DTC P0442 EVAPORATIVE EMISSION CONTROL SYSTEM LEAK DETECTED (SMALL LEAK)




1. OUTLINE OF DIAGNOSIS
Check if there is a leakage in fuel system or not, and perform the function diagnosis of valve.

In this system diagnosis, check for leakage and valve function is conducted by changing the fuel tank pressure and monitoring the pressure change using the fuel tank pressure sensor. When in 0.04 inch diagnosis, perform in the order of mode Z -> mode A -> mode B -> mode C and mode D; When in 0.02 inch diagnosis, perform in the order of mode A -> mode B -> mode C -> mode D and mode E.




0.04-inch Diagnosis




Mode Table for Evaporative Emission Control System Diagnosis




0.02-inch Diagnosis

2. ENABLE CONDITIONS




0.04-inch Diagnosis




0.02-inch Diagnosis

3. GENERAL DRIVING CYCLE

0.04-inch Diagnosis
Perform the diagnosis only once in 851 seconds or more after starting the engine, at a constant speed of 32 km/h (20 MPH) or more.
Pay attention to the fuel temperature and fuel level.

0.02-inch Diagnosis
Perform the diagnosis after 120 seconds or more after starting the engine, at a constant engine RPM of 30 km/h (19 MPH) or higher, to judge as NG or OK.
If OK/NG judgment is not possible, repeat the diagnosis.
Pay attention to the fuel temperature and fuel level.

4. DIAGNOSTIC METHOD

0.04-inch Diagnosis
Mode Z: (Purge control solenoid valve opening failure diagnosis)
When performing the leakage diagnosis of the EVAP system, the purge control solenoid valve must operate properly. Therefore, mode Z is used to diagnose a stuck open condition of the purge control solenoid valve by monitoring the tank pressure.

Note that if a purge control solenoid valve stuck open fault is detected, the EVAP system leakage diagnosis is cancelled.

Purge Control Solenoid Valve Stuck Open Diagnosis

DTC
P0457 Evaporative Emission Control System Leak Detected (Fuel Cap Loose/Off)




Diagnostic method
Purge control solenoid valve stuck open diagnosis is performed in mode Z as shown in the figure.

Purge Control Solenoid Valve Function Diagnosis

DTC
P0457 Evaporative Emission Control System Leak Detected (Fuel Cap Loose/Off)
Purge control solenoid valve functional diagnosis is performed by monitoring the tank pressure in mode Z.







Normality Judgment
Make OK judgment 3 seconds after Mode Z starts, and change to Mode A if OK.
- evptez - evptezha <= 0.4 kPa (3.0 mmHg, 0.12 inHg)
- evptezini - evptezha <= 0.4 kPa (3.0 mmHg, 0.12 inHg)

Judge normal when these calculations are completed.




Abnormality Judgment
If OK judgment cannot be made, extend Mode Z 16 seconds more, and Judge as NG when all the criteria below are completed in 16 seconds.




When judgment for purge control solenoid valve stuck open NG is made, end the evaporative diagnosis. Cancel the evaporative diagnosis when the OK/NG judgment for drain valve stuck closed and purge control solenoid valve stuck open cannot be made in Mode Z.

- evptezini, evptez <= 1.43 kPa (10.7 mmHg, 0.42 inHg)
- evptez - evptezha <= 0.87 kPa (6.5 mmHg, 0.26 inHg)
- evptezini - evptezha <= 0.87 kPa (6.5 mmHg, 0.26 inHg)
- No fuel sloshing of over 22(0.79 US gal, 0.67 Imp gal) for more than 40 seconds.

Judge as normal when all are established.

Leak Diagnosis

DTC
P0442 Evaporative Emission Control System Leak Detected (Small Leak)
P0457 Evaporative Emission Control System Leak Detected (Fuel Cap Loose/Off)

Diagnostic method
The diagnostic method consists of creating a sealed vacuum in the fuel tank and then determining the presence of leakage from the speed at which the tank internal pressure returns to atmospheric pressure.

Mode A: (Estimated evaporation gas amount)
Calculate the tank pressure change amount (P1) when using mode A. After calculating P1, switch to mode B.

Mode B: (Negative pressure sealed)
Introduce negative pressure in the intake manifold to the tank.
Approx. 0 -> -1.4 (0 -> -10.5, 0 -> -0.41) kPa (mmHg, inHg)
When the pressure above (desired negative pressure) is reached, enters Mode C.
In this case, if the tank pressure does not become the desired negative pressure, judge that there is a large leakage (10 seconds or 25 seconds) in the system.




Abnormality Judgment
Judge as NG (large leak) when the criteria are met.




Mode C: (Check pressure rise)
Stop the introduction of negative pressure. (Wait until the tank pressure returns to the start level of P2 calculation.)
Change to Mode D when the tank pressure returns to the start level of P2 calculation.
Judge immediate OK and change to Mode E when it does not return in spite of spending the specified time.

Mode D: (Measure amount of negative pressure change)
Monitor the tank pressure change amount when using mode D. In this case, the tank pressure increases, (nears atmospheric pressure) because evaporation occurs. However, if any leakage exists, the pressure increases additionally in proportion to this leakage. The pressure variation of this tank is P2. After calculating P2, perform a small leak diagnosis according to the items below.







When Mode D is ended
Assign tank variations measured in Mode A and Mode B; P1 and P2, to the formula below, judge small leaks in the system. If the measured judgment value exceeds the threshold value, it is judged to be a malfunction.
Judge as NG when the criteria below are completed and Judge as OK when not completed.

Time Needed for Diagnosis: 30 to 100 seconds
0.02-inch Diagnosis DTC

DTC
P0456 Evaporative Emission Control System Leak Detected (very small leak)

Diagnostic method
The diagnostic method consists of creating a sealed vacuum in the fuel tank and then determining the presence of leakage from the speed at which the tank internal pressure returns to atmospheric pressure.

Mode A: (0 Point Compensation)
When pressure in tank is high, wait for 0 point 0 kPa (Near 0 mmHg, 0 inHg) to return.Shift to mode B when 0 point returns.
Cancel the diagnosis when 0 point does not return in the specified time.

Mode B: (Negative pressure introduced)
Introduce negative pressure in the intake manifold to the tank.
Approx. 0 -> -2.0 kPa (0 mmHg -> -15 mmHg, 0 -> -0.59 inHg)
When the pressure above (desired negative pressure) is reached, Mode C is entered.
Cancel the diagnosis when the targeted pressure in the tank is not reached.

Mode C: (Negative pressure maintained)
Stop the introduction of negative pressure and wait until the tank pressure returns to the start level of P2 calculation.
Change to Mode D either when the tank pressure returns to the start level of P2 calculation, or when the predetermined amount of time has passed.




Mode D: (Calculate the amount of negative pressure change)
Monitor the tank pressure in mode D, calculate (P2) the pressure change in the tank, and measure the time (evpdset) for the tank pressure to return when calculation of P2 is completed. Shift to mode E when pressure returns. Make an advance OK judgment using the value of P2, or cancel, when the pressure in the tank does not return after calculation of P2 is completed even when the predetermined amount of time has passed.
When the given conditions are established, it is OK.

Mode E: (Evaporation occurrence amount calculation)
Calculate the change of tank pressure with the time evpdset to Judge as NG/OK according to the value of P1.
(ambiguous determination acceptable.)




Abnormality Judgment
When the given conditions are established, it is NG.
Map 3 Failure diagnosis reference limit for 0.02 in leaks for evaporative emission control system diagnosis




Normality Judgment
When the given conditions are established, it is OK.

5. DTC CLEAR CONDITION
- When the OK idling cycle is completed 40 times in a row
- When "Clear Memory" is performed

6. MALFUNCTION INDICATOR LIGHT CLEAR CONDITIONS
- When the OK driving cycle is completed 3 times in a row
- When "Clear Memory" is performed

7. FAIL SAFE
None

8. ECM OPERATION AT DTC SETTING
- Memorize the freeze frame data. (For test mode $02)
- Memorize the diagnostic value and trouble standard value. (For test mode $06)