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Home >> Subaru >> 2009 >> Tribeca Base >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Diagnostic Trouble Code (DTC) Detecting Criteria (H6DO) >> Diagnostic Trouble Code (DTC) Detecting Criteria >> DTC P0442 Evaporative Emission Control System Leak Detected (Small Leak) >> Diagnostic Method

Diagnostic Method

Purge control solenoid valve stuck open fault diagnosis 

DTC

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

Purpose of Mode Z 

When performing the leakage diagnosis of EVAP system, the purge control solenoid valve must operate normally. Therefore, mode Z is used to diagnose the purge control solenoid valve stuck open condition. Note that if a purge control solenoid valve stuck open fault is detected, the EVAP system leakage diagnosis is cancelled.

DIAGNOSTIC METHOD 

Purge control solenoid valve functional diagnosis is performed by monitoring the tank pressure in mode Z.

If OK judgement cannot be made, extend Mode Z, and Judge as NG when the following conditions are established after predetermined amount of time.

Judgement Value 

JUDGEMENT VALUE REFERENCE

Malfunction Criteria Threshold Value DTC
evptez - evptezha > 0.6 kPa (4.5 mmHg, 0.2 inHg) P0457
evptezini ≤ 0.4 kPa (2.9 mmHg, 0.1 inHg)  
Time of 2 (0.53 US gal, 0.44 lmp gal) or more fuel no sloshing ≥ 40000 ms  

Time Needed for Diagnosis:  5000 ms + 3000 ms + 13000 ms

Malfunction Indicator Light Illumination:  Illuminates when malfunction occurs in 2 continuous driving cycles.

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

Judge as OK and change to Mode A when the following conditions are established after predetermined time has passed since Mode Z started.

Judgement Value 

JUDGEMENT VALUE REFERENCE

Malfunction Criteria Threshold Value DTC
evptez - evptezha ≤ 0.4 kPa (3 mmHg, 0.1 inHg) P0457

Normal 

Fig 1: Fuel Tank Pressure Graph (Normal)
G06342685Courtesy of SUBARU OF AMERICA, INC.

evptez - evptezha ≤ 0.4 kPa (3 mmHg, 0.1 inHg) Normal when above is established

Time Needed for Diagnosis:  5000 ms + 3000 ms

Purge control solenoid valve Open Fixation 

Fig 2: Fuel Tank Pressure Graph (Purge Control Solenoid Valve Open Fixation)
G06342686Courtesy of SUBARU OF AMERICA, INC.

Judge as abnormal 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)

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 kPa (0 → -10.5 mmHg, 0 → -0.4 inHg)

When the pressure above (desired negative pressure) is reached, enters Mode C.

In this case, if the tank pressure does not reach the target negative pressure, judge that there is a large leakage in the system and terminate the evaporative emission control system diagnosis.

Abnormality Judgement 

Judge as NG (large leakage) when the following conditions are established.

Judgement Value 

JUDGEMENT VALUE REFERENCE

Malfunction Criteria Threshold Value DTC
Time to reach target negative pressure ≥ 10000 ms + 25000 ms P0457
or    
Mode B time ≥ 10000 ms  
(Min. pressure value in tank when in mode B)-(Tank pressure when mode B started) > -0.5 kPa (-4 mmHg, -0.2 inHg)  

Time Needed for Diagnosis:  5000 ms + 3000 ms + 10000 ms + 10000 ms + 25000 ms

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.

TANK PRESSURE REFERENCE

Tank pressure when starting calculation of P2 Time for advanced OK judgement
-1.3 kPa (-9.75 mmHg, -0.4 inHg) 14000 ms

Time Needed for Diagnosis:  5000 ms + 3000 ms + 10000 ms + 10000 ms + 25000 ms + 14000 ms

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 barometric 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 D, P1 and P2, to the formula below, judge small leaks in the system. If the measured judgement value exceeds the threshold value, it is judged to be a malfunction.

Abnormality Judgement 

Judge as NG when the following conditions are established within the predetermined time. Judge as OK and clear the NG if the following conditions are not established within the predetermined time.

Judgement Value 

JUDGEMENT VALUE REFERENCE

Malfunction Criteria Threshold Value DTC
P2 - 1.5 - x P1 > Value of Map 5 P0442
P2: Tank pressure that changes every 10000 ms in mode D    
P1: Tank pressure that changes every 10000 ms in mode A    
*1.5-: Evaporation amount compensation value when below negative pressure (Amount of evaporation occurrence increases as a vacuum condition increases.)

Map 5 Malfunction Criteria limit for evaporation diagnosis 

EVAPORATION DIAGNOSIS REFERENCE

Fuel temperature vs. Fuel level 25 °C (77 °F) 30 °C (86 °F) 35 °C (95 °F) 40 °C (104 °F) 45 °C (113°F)
0 (0 US gal, 0 lmp gal) 0.3 kPa (2.1 mmHg, 0.1 inHg) 0.3 kPa (2.2 mmHg, 0.1 inHg) 0.3 kPa (2.3 mmHg, 0.1 inHg) 0.3 kPa (2.35 mmHg, 0.1 inHg) 0.3 kPa (2.4 mmHg, 0.1 inHg)
10 (2.64 US gal, 2.2 lmp gal) 0.3 kPa (2.1 mmHg, 0.1 inHg) 0.3 kPa (2.2 mmHg, 0.1 inHg) 0.3 kPa (2.3 mmHg, 0.1 inHg) 0.3 kPa (2.35 mmHg, 0.1 inHg) 0.3 kPa (2.4 mmHg, 0.1 inHg)
20 (5.28 US gal, 4.4 lmp gal) 0.3 kPa (2.3 mmHg, 0.1 inHg) 0.3 kPa (2.4 mmHg, 0.1 inHg) 0.3 kPa (2.5 mmHg, 0.1 inHg) 0.3 kPa (2.6 mmHg, 0.1 inHg) 0.4 kPa (2.7 mmHg, 0.1 inHg)
30 (7.93 US gal, 6.6 lmp gal) 0.4 kPa (2.9 mmHg, 0.1 inHg) 0.4 kPa (3.05 mmHg, 0.1 inHg) 0.4 kPa (3.15 mmHg, 0.1 inHg) 0.4 kPa (3.25 mmHg, 0.1 inHg) 0.4 kPa (3.35 mmHg, 0.1 inHg)
40 (10.57 US gal, 8.8 lmp gal) 0.4 kPa (2.9 mmHg, 0.1 inHg) 0.4 kPa (3.15 mmHg, 0.1 inHg) 0.4 kPa (3.3 mmHg, 0.1 inHg) 0.5 kPa (3.4 mmHg, 0.1 inHg) 0.5 kPa (3.5 mmHg, 0.1 inHg)
50 (13.21 US gal, 11 lmp gal) 0.4 kPa (3.2 mmHg, 0.1 inHg) 0.4 kPa (3.3 mmHg, 0.1 inHg) 0.5 kPa (3.5 mmHg, 0.1 inHg) 0.5 kPa (3.6 mmHg, 0.1 inHg) 0.5 kPa (3.7 mmHg, 0.1 inHg)
60 (15.85 US gal, 13.2 lmp gal) 0.4 kPa (3.2 mmHg, 0.1 inHg) 0.4 kPa (3.3 mmHg, 0.1 inHg) 0.5 kPa (3.5 mmHg, 0.1 inHg) 0.5 kPa (3.6 mmHg, 0.1 inHg) 0.5 kPa (3.7 mmHg, 0.1 inHg)

Time Needed for Diagnosis:  5000 ms + 3000 ms +10000 ms +10000 ms + 25000 ms +14000 ms +10000 ms

Malfunction Indicator Light Illumination:  Illuminates when malfunction occurs in 2 continuous driving cycles.

Leak Diagnosis 

DTC

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

Mode A: (0 point compensation) 

When the pressure in the tank is not near 0 mmHg, wait until it returns to 0 point (near 0 mmHg). Shift to mode B when returned to the 0 point. 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 kPa (0 → -15 mmHg, 0 → -0.6 inHg)

When the pressure above (desired negative pressure) is reached, enters Mode C.

When the tank internal pressure does not reach the target negative pressure, the diagnosis is cancelled.

Mode C: (Negative pressure maintained) 

Stop the introduction of negative pressure. (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 the pressure change in the tank (P2), and measure the time (evpdset) for the tank pressure to change to the Mode E shifting pressure. When the Mode E shifting pressure is reached, Mode E is entered. If it does not change to the Mode E shifting pressure after the predetermined amount of time has passed, make advanced OK judgement or cancel the diagnosis according to the value of P2.

Normality Judgement 

Judge as OK when the following conditions are established.

Judgement Value 

JUDGEMENT VALUE REFERENCE

Malfunction Criteria Threshold Value
Advanced OK judgement 1 
  Mode D time ≥ 0 ms + 20000 ms
  Tank internal pressure ≤ Value of Map 6
Advanced OK judgement 2 
  Mode D time ≥ 0 ms + 200000 ms
  P2 ≤ Value of Map 7

Map6 

FUEL LEVEL REFERENCE

Fuel level ( , US gal, lmp gal) 0, 0, 0 10, 2.64, 2.2 20, 5.28, 4.4 30, 7.93, 6.6 40, 10.57, 8.8 50, 13.21, 11 60, 15.85, 13.2
Tank pressure (kPa, mmHg, inHgl) -1.9, -13.9,-0.5 -1.9, -13.9, -0.5 -1.8, -13.8, -0.5 -1.8, -13.7, -0.5 -1.8, -13.6, -0.5 -1.8, -13.5, -0.5 -1.8, -13.5, -0.5

Map7 

FUEL LEVEL REFERENCE

Fuel level ( , US gal, lmp gal) 0, 0, 0 10, 2.64, 2.2 20, 5.28, 4.4 30, 7.93, 6.6 40, 10.57, 8.8 50, 13.21, 11 60, 15.85, 13.2
Tank pressure (kPa, mmHg, inHgl) 0.9, 7, 0.3 0.9, 7, 0.3 0.9, 7.05, 0.3 0.9, 7.1, 0.3 1.1, 8.2, 0.3 1.3, 9.6, 0.4 1.3, 9.6, 0.4

Mode E: (Evaporation occurrence amount calculation) 

Calculate the change of tank pressure with the time evpdset (P1) to judge as NG/OK according to the value of P1. (ambiguous determination acceptable).

Judge as NG when the following conditions are established.

Judgement Value 

JUDGEMENT VALUE REFERENCE

Malfunction Criteria Threshold Value
P1 < Value of Map 8

Map 8 Malfunction Criteria limit for evaporation diagnosis 

EVAPORATION DIAGNOSIS REFERENCE

Time (evpdset) vs. Fuel level 0 ms 50000 ms 65000 ms 120000 ms 150000 ms 200000 ms
0 (0 US gal, 0 lmp gal) 0 kPa (0 mmHg, 0 inHg) 0.2 kPa (1.4 mmHg, 0.1 inHg) 0.2 kPa (1.84 mmHg, 0.1 inHg) 0.2 kPa (1.84 mmHg, 0.1 inHg) 0.2 kPa (1.84 mmHg, 0.1 inHg) 0.2 kPa (1.84 mmHg, 0.1 inHg)
10 (2.64 US gal, 2.2 lmp gal) 0 kPa (0 mmHg, 0 inHg) 0.2 kPa (1.4 mmHg, 0.1 inHg) 0.2 kPa (1.84 mmHg, 0.1 inHg) 0.2 kPa (1.84 mmHg, 0.1 inHg) 0.2 kPa (1.84 mmHg, 0.1 inHg) 0.2 kPa (1.84 mmHg, 0.1 inHg)
20 (5.28 US gal, 4.4 lmp gal) 0 kPa (0 mmHg, 0 inHg) 0.2 kPa (1.54 mmHg, 0.1 inHg) 0.2 kPa (1.76 mmHg, 0.1 inHg) 0.2 kPa (1.76 mmHg, 0.1 inHg) 0.2 kPa (1.76 mmHg, 0.1 inHg) 0.2 kPa (1.76 mmHg, 0.1 inHg)
30 (7.93 US gal, 6.6 lmp gal) 0 kPa (0 mmHg, 0 inHg) 0.2 kPa (1.68 mmHg, 0.1 inHg) 0.2 kPa (1.68 mmHg, 0.1 inHg) 0.2 kPa (1.68 mmHg, 0.1 inHg) 0.2 kPa (1.68 mmHg, 0.1 inHg) 0.2 kPa (1.68 mmHg, 0.1 inHg)
40 (10.57 US gal, 8.8 lmp gal) 0 kPa (0 mmHg, 0 inHg) 0.2 kPa (1.315 mmHg, 0.1 inHg) 0.2 kPa (1.315 mmHg, 0.1 inHg) 0.2 kPa (1.315 mmHg, 0.1 inHg) 0.2 kPa (1.315 mmHg, 0.1 inHg) 0.2 kPa (1.315 mmHg, 0.1 inHg)
50 (13.21 US gal, 11 lmp gal) 0 kPa (0 mmHg, 0 inHg) 0.1 kPa (0.95 mmHg, 0 inHg) 0.1 kPa (0.95 mmHg, 0 inHg) 0.1 kPa (0.95 mmHg, 0 inHg) 0.1 kPa (0.95 mmHg, 0 inHg) 0 kPa (0 mmHg, 0 inHg)
60 (15.85 US gal, 13.2 lmp gal) 0 kPa (0 mmHg, 0 inHg) 0.1 kPa (0.95 mmHg, 0 inHg) 0.1 kPa (0.95 mmHg, 0 inHg) 0.1 kPa (0.95 mmHg, 0 inHg) 0.1 kPa (0.95 mmHg, 0 inHg) 0 kPa (0 mmHg, 0 inHg)

Time Needed for Diagnosis:  Value of Map1+ Value of Map2 + 20000 ms + 0 + Value of Map2 + 0 ms + 200000 ms + Value of Map3 + 0 ms + 200000 ms

Malfunction Indicator Light Illumination:  Illuminates when malfunction occurs in 2 continuous driving cycles.

Judge as OK when the following conditions are established.

Judgement Value 

JUDGEMENT VALUE REFERENCE

Malfunction Criteria Threshold Value
P1 > Value of Map 9

Map 9 Malfunction Criteria limit for evaporation diagnosis 

EVAPORATION DIAGNOSIS REFERENCE

Time (evpdset) vs. Fuel level 0 ms 50000 ms 65000 ms 120000 ms 150000 ms 200000 ms
0 (0 US gal, 0 lmp gal) 0.1 kPa (1 mmHg, 0 inHg) 0.4 kPa (2.88 mmHg, 0.1 inHg) 0.4 kPa (3.28 mmHg, 0.1 inHg) 0.4 kPa (3.28 mmHg, 0.1 inHg) 0.4 kPa (3.28 mmHg, 0.1 inHg) 0.4 kPa (3.28 mmHg, 0.1 inHg)
10 (2.64 US gal, 2.2 lmp gal) 0.1 kPa (1 mmHg, 0 inHg) 0.4 kPa (2.88 mmHg, 0.1 inHg) 0.4 kPa (3.28 mmHg, 0.1 inHg) 0.4 kPa (3.28 mmHg, 0.1 inHg) 0.4 kPa (3.28 mmHg, 0.1 inHg) 0.4 kPa (3.28 mmHg, 0.1 inHg)
20 (5.28 US gal, 4.4 lmp gal) 0.1 kPa (1 mmHg, 0 inHg) 0.4 kPa (2.91 mmHg, 0.1 inHg) 0.4 kPa (3.11 mmHg, 0.1 inHg) 0.4 kPa (3.11 mmHg, 0.1 inHg) 0.4 kPa (3.11 mmHg, 0.1 inHg) 0.4 kPa (3.11 mmHg, 0.1 inHg)
30 (7.93 US gal, 6.6 lmp gal) 0.1 kPa (1 mmHg, 0 inHg) 0.4 kPa (2.93 mmHg, 0.1 inHg) 0.4 kPa (2.93 mmHg, 0.1 inHg) 0.4 kPa (2.93 mmHg, 0.1 inHg) 0.4 kPa (2.93 mmHg, 0.1 inHg) 0.4 kPa (2.93 mmHg, 0.1 inHg)
40 (10.57 US gal, 8.8 lmp gal) 0.1 kPa (1 mmHg, 0 inHg) 0.4 kPa (2.76 mmHg, 0.1 inHg) 0.4 kPa (2.76 mmHg, 0.1 inHg) 0.4 kPa (2.76 mmHg, 0.1 inHg) 0.4 kPa (2.76 mmHg, 0.1 inHg) 0.4 kPa (2.76 mmHg, 0.1 inHg)
50 (13.21 US gal, 11 lmp gal) 0.1 kPa (1 mmHg, 0 inHg) 0.3 kPa (2.58 mmHg, 0.1 inHg) 0.3 kPa (2.58 mmHg, 0.1 inHg) 0.3 kPa (2.58 mmHg, 0.1 inHg) 0.3 kPa (2.58 mmHg, 0.1 inHg) 0.2 kPa (1.3 mmHg, 0.1 inHg)
60 (15.85 US gal, 13.2 lmp gal) 0.1 kPa (1 mmHg, 0 inHg) 0.3 kPa (2.58 mmHg, 0.1 inHg) 0.3 kPa (2.58 mmHg, 0.1 inHg) 0.3 kPa (2.58 mmHg, 0.1 inHg) 0.3 kPa (2.58 mmHg, 0.1 inHg) 0.2 kPa (1.3 mmHg, 0.1 inHg)

Time Needed for Diagnosis:  Value of Map1+ Value of Map2 + 20000 ms + 0 + Value of Map2 + 0 ms + 200000 ms + Value of Map3 + 0 ms + 200000 ms