SAAB WIS ONLINE

P0442

Read the instructions below then start the fault diagnostic procedure.

Symptom: CHECK ENGINE. Possible smell of petrol.

P0442


EVAP. Small Leakage in System.


Fault symptoms


• CHECK ENGINE.

• Possible smell of petrol.


On-Board Diagnostics

Type of diagnosis:


- Once per driving cycle. It is interrupted once fault criteria have been fulfilled or OK has been reported. Restarts next driving cycle.


Enable criteria: (Conditions that must be fulfilled for diagnostics to be performed.)


- Global conditions for this diagnostic trouble code: When starting the engine, the atmospheric pressure must exceed 78 kPa and the temperature of the coolant and the intake air must exceed -7°C.

- Test 1: Coolant temperature on starting lower than 40°C. Purge active. Idling. Maximum one change in status of the brake light switch. Purge adaptation higher than -7 %. Intake air pressure at least 20 kPa lower than atmospheric pressure. Car stationary for 5s.

The diagnosis will commence once the above criteria have been fulfilled. If the diagnosis is interrupted, vehicle speed will have to exceed 0 on one occasion before the diagnosis is allowed to restart. The diagnosis then proceeds as described in the following phases: A) The shut-off valve is activated at the same time as the purge is interrupted for 3.5s. Meanwhile, the tank pressure is monitored. B) The pulse ratio of the purge valve is set to 18% until the tank pressure has dropped by 0.6 kPa, whereupon the purge will be interrupted. The drop in pressure must take only 20s. If it takes place too rapidly during this phase, the diagnosis will be interrupted because there is too much fuel in the tank (more than 85%). C) The tank pressure is monitored for a maximum of 6s.

- Test 2: Coolant temperature on starting above 40°C or Test 1 indicated a leak. Approved transition diagnosis for oxygen sensor 1. Purge active. Idling. Maximum one change in status of the brake light switch. Purge adaptation higher than -6 %. Intake air pressure at least 20 kPa lower than atmospheric pressure. Car stationary for 5s.

The diagnosis will commence once the above criteria have been fulfilled. If the diagnosis is interrupted, vehicle speed will have to exceed 0 on one occasion before the diagnosis is allowed to restart. The diagnosis then proceeds as described in the following phases: A) The shut-off valve is activated at the same time as the purge is interrupted for 3.5s. Meanwhile, the tank pressure is monitored. B) The pulse ratio of the purge valve is set to 18% until the tank pressure has dropped by 0.6 kPa, whereupon the purge will be interrupted. The drop in pressure must take only 20s. If it takes place too rapidly during this phase, the diagnosis will be interrupted because there is too much fuel in the tank (more than 85%). C) The tank pressure is monitored for a maximum of 6s.


Fault criteria: (When enable criteria have been fulfilled, diagnostics will check if the fault criteria have been fulfilled.)


- If the pressure drops by more than 0.25 kPa in phase A, an internal leak will have been detected in the evap canister purge valve. If the pressure cannot be reduced to 0.6 kPa within 20s in phase B, a major leak will have been detected. If the pressure rises too rapidly within 6s in phase C, a minor leak will have been detected.

- Diagnostic trouble codes are generated when the fault criteria in both Test 1 and Test 2 have been fulfilled during the same driving cycle and the dependents are OK.

P0441 for faults during phase A. P0455 for faults during phase B. P0442 for faults during phase C.


Dependents: (Once fault criteria have been fulfilled, a number of other diagnostics must report OK before the diagnostic trouble code can finally be generated.)


- P0444, P0445, P0501, P0502, P0506, P0507, P1444, P1445, P1576 and P1577.


System reaction to a fault: (Once the fault criteria have been fulfilled, certain measures will sometimes be taken.)


- If a leak is detected during Test 1 or Test 2, the message “TIGHTEN FUEL FILLER CAP” will be displayed on SID. The message is displayed after each test that detects a leak but only twice in succession. The diagnosis must report OK on one occasion for it to be possible to display the message again.


OK report: (This diagnosis may be included as a dependent to another diagnosis and must therefore report OK even if it is continuous. The OK report is also used in fault handling to count down the fault counter.)


- Test 1 or Test 2 performed once and fault criteria not fulfilled.


Fault handling: (Refer to section “Fault diagnosis, general” for more information.)


- Type III.


Diagnostic help

Fault diagnosis concerns leakage.

Diagnostic tool functions related to this fault:


• Diagnostic status for the diagnosis.

• Activation of EVAP diagnostics.


Refer also to the description of readings under ”Fault diagnosis, general” for more information

Note

For a diagnostic trouble code to be generated, first Test 1 and then Test 2 must indicate a leak during the same driving cycle. To achieve this, the coolant temperature on starting the engine must be below 40°C (104°F). Consequently, the diagnostic trouble code cannot be generated if the engine is started while still warm.

As a final check of the rectified fault, the diagnostic tool activation command can be used to initiate Test 1 irrespective of the starting temperature.