SAAB WIS ONLINE

P0300

Read the instructions below then start the fault diagnostic procedure.

Symptom: CHECK ENGINE lamp is on or flashing. Engine running unevenly during misfiring. Possibly other diagnostic trouble codes present.

P0300


Misfiring. More than one cylinder.


Fault symptoms

CHECK ENGINE lamp is on or flashing. Engine running unevenly during misfiring. Possibly other diagnostic trouble codes present.

Conditions

The number of misfires required for the exhaust emissions to reach prohibited levels or damage the catalytic converter is stored in the control module memory in a matrix that is dependent on load and engine speed. A diagnostic trouble code will be generated if the misfires exceed the value in the matrix. Several cylinders misfiring.

Diagnostic help

The cause of the misfiring can be:


• Low fuel level in the tank. This will be indicated by diagnostic trouble code P1416 also being generated

• fault in fuel system

low fuel pressure

EVAP canister purge valve continuously open

incorrect voltage from oxygen sensor 1

defective injectors

• fault in ignition system

incorrect spark plugs

incorrect ignition discharge module

• fault in basic engine

deficient compression

• fault in common components, pressure sensor, main relay, engine coolant temperature sensor


The cause of incorrectly detected misfiring, diagnostic trouble code P0300 without misfiring, can be:

control module pin 17 or 18 short-circuited to ground

Momentary misfiring can be read with the diagnostic tool


- Select " Data Display / Output Control (New)".



- Select " Misfire Cyl 1".


The remaining cylinders can also be selected.

Checking the wiring harness. Intermittent faults may occur in connection with short circuits and open circuits. Jiggle the wiring harness at several points and in several directions to locate any problems in the wiring, including intermediate connectors. Observe the multimeter, scan tool or test lamp during the check.

Warning

The electronic ignition system generates a tension of 40 000 volts. This tension can be lethal for people with heart problems or pacemakers. The ignition system must therefore be treated with the greatest respect.


Important

The ignition discharge module must be standing with the ignition coils facing down during the test so that the transformer oil will provide good insulation to the high tension part of the ignition coil