0.04 inch Diagnosis
Mode A: (Estimation of evaporation gas yield)
The amount of change of tank pressure (P1) in Mode A is calculated. After calculating P1, change to Mode B.
Mode B: (Seal negative pressure)
Introduce the negative pressure in the intake manifold to the tank.
Approx. 0 --> -1.4 kPa (0 --> -10.5 mmHg, 0 --> -0.41 inHg)
When the pressure above (desired negative pressure) is reached, Mode C is entered.
In this case, if the tank pressure does not become the desired negative pressure, judge that there is a large leakage in the system and judge as large leak (10 or 25 seconds).
Abnormality Judgment
Judge NG (large leak) when the criteria below are completed in the specified time.
Judgment Value
| Malfunction Criteria | Threshold Value | DTC |
|---|---|---|
| Time before reaching desired negative pressure | >/= 25 seconds | P0457 |
| Or time for Mode B | >/= 10 seconds | |
| (Min. value of tank pressure during Mode B) - | < -0.3 kPa (-2 mmHg, | |
| (Tank pressure when Mode B started) | -0.08 inHg) |
Mode C: (Check increasing pressure)
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 when P2 calculation started | Time for immediate OK judgment |
| -1.3 kPa (-9.75 mmHg, - 0.38 inHg) | 15 seconds |
Mode D: (Measurement of negative pressure changes)
Monitor the pressure variation in the tank in Mode Z. In this case, the tank pressure increases, that is, the pressure becomes as high as the atmospheric air pressure, because evaporator is generated. 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 following small leak diagnosis.