T8 / P0300 00
Read the instructions below then
start the fault diagnostic procedure.
Symptom: Fault indicator lamp (for further information see WIS Fault diagnosis, general)
(Check Engine lamp flashes if diagnostics has detected a misfire that is harmful to the catalytic converter).
Uneven running and misfiring.
Random Misfire Detected.
Fault symptom
Fault indicator lamp (for further information see WIS Fault diagnosis, general)
(Check Engine lamp flashes if diagnostics has detected a misfire that is harmful to the catalytic converter).
Uneven running and misfiring.
On-board diagnosis
Type of diagnosis:
| Each misfire is registered and evaluated two different ways depending on the type of misfire. |
| • | Harmful to the catalytic converter. |
Enable criteria:
| General conditions for this DTC |
| • | Positive engine torque (negative torque = engine braking). |
| • | Combustion signals from CDM are registered. |
| • | Total number of combustion signals registered. |
| • | The number of times no combustion signal is sent is tallied per cylinder every 200 engine revolutions. The total number of permissible misfires per 200 revolutions is indicated in a load and rpm-dependent matrix. |
Fault criteria:
| • | Total number of missing combustion signals more than 3%. |
| • | The number of times no combustion signal was sent exceeds the number of permissible misfires. More than one cylinder has misfired. |
Dependent:
| P1312, P1315, P1341, P1342, P1343, P1344 |
System reaction to a fault:
OK report:
| OK report occurs during ignition off, if no Fault report has been made during the driving cycle. |
Fault handling:
| • | (See section Fault handling II, "Emission-related misfiring or fault in fuel system" for more information.) |
| • | (See section Fault handling I, "Catalyst damaging misfiring" for more information). |
Checking the wiring harness
Move the wiring harness at several spots and in several directions to reveal intermittent breaks and short-circuits. Check switches, connectors and crimp connections for oxidation, retracted pins and pin clamping force.
Diagnostic help
Diagnosis regards:
| Fuel/air mixture too rich or too lean, insufficient compression, poor spark plugs causing incomplete combustion. |
| A cursory check is carried out on connectors and hoses. Then a through check is carried out on compression, ignition timing and fuel system. |
Functions in the diagnostic tool related to the fault:
| • | Airmass Deviation from Calculated |
| (See also description of readings/activations in diagnostic tool) |
