AfterSales Diagnostic Sheet
MAS002358
(BOL 20-15)

From: Aftersales - TSO
To: Maserati Network
Auburn Hills, MI | October 19, 2020

Spark plugs checklist (engine malfunction/engine
warning light on)
Issue: noise/vibration due to engine malfunction and/or Engine warning light on (solid or
flashing ). Possibly any of the following DTCs: P13D1-P13D0-P0300-P0301-P0302-P0303P0304-P0305-P0306 stored in the ECM fault memory.
Models: M157/M156/M161 V6 Gasoline engines
Issue description:
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Check Engine warning light on;
Reduced engine performance;

Conditions: while driving with possible engine warning light on
Ecu errors: the following DTC: P13D1-P13D0-P0300-P0301-P0302-P0303-P0304-P0305P0306 may be set in the ECM fault memory.
Troubleshooting:
Preliminary checks:
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If the car is in PDI, check if the shipping mode is ON. If yes, first deactivate it and then
test the car again. If the issue is still present proceed to the next step.

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Save a scan report of the DTCs and Parameters of the ECM module.

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Check the fuel gauge for the amount of fuel in the tank. If the fuel tank is too low,
restore the correct fuel level and retest. (At least to ¼ mark on the fuel gauge)

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If the anomaly is a Customer complaint, acquire information on driving style and the
conditions when the issue occurred.

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CHECK SPARK PLUGS

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Verify that the spark plugs installed in the vehicle are factory recommended and
tightened to the prescribed tightening torque (18 Nm for the V6).

NOTE: It should be noted that the simple loss of tightening torque is difficult to associate
with misfire events. The misfire events can only be generated in the event of partial or total
loss of tightening torque of a spark plug


Remove the spark plugs and make sure that:

the ceramic insulator is not broken
the electrode is not deformed or broken
the electrode is not melted
the electrode is not crushed
the electrode has no abrasions
the distance between the electrodes is correct (0,5-0,6 millimeters for the V6)
the electrodes show no signs of dirt or carbon deposits
there is no rust
the hex nut portion has no defects
there are no cracks in the insulation caused by incorrect use of a spark plug tightening
socket
 there is no damage in the spark plug insertion area on the ignition coil
 there are no burn marks on the spark plug insulation
 Check the internal resistance of the spark plug. Measure the resistance between the
end of the spark plug and the central part of the electrode. Check that the resistance
is between 3 and 7.5 kOhm, if not, replace it.
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If one of the anomalies described above is found (with the exception of signs of dirt or carbon
deposits), replace the damaged spark plug according to the instructions of the Workshop
Manual. Then test the car again.
NOTE: If there are only signs of dirt or carbon deposits, proceed with the following cleaning
procedure and retest the vehicle:

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SPARK PLUG CLEANING PROCEDURES

1) Start the car with cold engine temperature.
2) Wait until the engine temperature is warmed up.
3) With the gearbox in P position, accelerate for 3 minutes at 3000 rpm.
4) Turn the engine off.
Considerations: if after performing all of the above checks the anomaly is still present, open a
BOL as a support request and attaching the results of each check.