SAAB WIS ONLINE

P1394

Read the instructions below then start the fault diagnostic procedure.

Symptom: CHECK ENGINE. Running unevenly and misfiring.

P1394


Cylinder 4 Misfire Detected. Catalyst Damaging. Fuel Level Low.


Fault symptoms


CHECK ENGINE.

Running unevenly and misfiring.


On-Board Diagnostics

Type of diagnosis:


- Continuous. But interrupted when fault criteria fulfilled and will not restart until next driving cycle.


Enable criteria:


- General conditions for this trouble code: Atmospheric pressure must exceed 72 kPa and the engine coolant and intake air temperature must exceed -7°C.

- Engine started. Fuel level below 4 litres. Main relay voltage exceeding 10V. Ignition discharge module combustion signals registered. The number of missing combustion signals is accumulated for each cylinder during 200 engine revolutions. The total number of accepted misfires during 200 engine revolutions is specified in a load and engine speed-dependent matrix.


Fault criteria:


- Number of missing combustions exceeding number of accepted misfires.


Dependents:


- P1312 and P1334.


System reaction to a fault:


- Under high engine loads, closed loop will be blocked while misfiring occurs.

- Fuel to a cylinder is shut off if misfiring is confirmed by the control module.


OK report:


- Provided the fault criteria are not fulfilled during the driving cycle the OK report occurs at ignition off before the engine stalls. Two types of OK reports can be given: Type 1: If a DTC is already stored for the diagnosis and similar operating conditions have occurred (coolant temperature above or below 71°C, engine speed ±375 rpm and load ±10%). Type 2: If there is no DTC stored for the diagnosis or similar operating conditions have not occurred


Fault handling: (See section Fault handling I, catalytic converter harmful misfiring for more information.)


- Type I.


Diagnostic help

If any other trouble codes have been generated, check whether fault diagnosis should start with them. Drive the car in the load and engine speed range shown by Freeze Frame. If the engine does not misfire, the trouble code was probably due to the fuel level being too low. Drive the car so that the catalyst diagnosis is performed. If necessary, change the catalytic converter.

If the engine misfires during test driving, conduct a general inspection of connectors and hoses, and then a thorough check of compression, ignition and fuel system.

Functions in the diagnostic tool related to the fault:


Diagnostic status for the diagnosis.

Misfire counter for the relevant cylinder.

Activation of misfire counter resetting.

Activating ignition trigger for relevant cylinder.

Activating injector test for relevant cylinder.

Activation and deactivation of the fuel supply to the cylinder in question.


See also description on activating under "Activate" menu for more information.

Check the wiring

Jiggle the leads and in-line connectors at various points and in different directions to detect any intermittent breaks or short circuits in the wiring. Observe the multimeter, test lamp or diagnostic tool while doing this.

See P1391 .