Engine/Eng. Controls - Crank, No Start/ECT Sensor Faults

SI M11 01 11
Engine

July 2012
Technical Service

This Service Information bulletin supersedes SI M11 01 11 dated February 2012.

[NEW] Note: N16 and N14 JCW engines have been removed. For diagnosing N16 and N14 JCW engines, refer to SI M11 04 12.

[NEW] designates changes to this revision

SUBJECT
[NEW] N18: Engine Crank, No Start and/or Engine Coolant Temperature Sensor Faults

MODEL
[NEW] R55, R56, R57, R58, R59 and R60

SITUATION 1
The engine either exhibits a crank, no start or a hard start (long crank) usually on a cold engine. No faults are stored in the DME.

[NEW] SITUATION 2
The Service Engine Soon lamp is illuminated with one or more of the following fault codes stored:

N18

^ 0x2943 coolant temperature sensor, signal change too fast

^ 0x2937 coolant temperature sensor, electrical: short circuit to positive

^ 0x2936 coolant temperature sensor, electrical: short circuit to earth

^ 0x293A coolant temperature sensor, plausibility, cold start: temperature too high

^ 0x2947 coolant temperature sensor, signal: fixed on low

CAUSE
Poor solder contacts in the engine coolant temperature sensor.

The sensor is integrated into the engine thermostat housing.

[NEW] PROCEDURE

1. If no fault codes are stored:

^ Using ISTA/D, read out the ambient air temperature and engine coolant temperature in the DME through Diagnostic Query.

^ If the vehicle has been sitting overnight, these two temperatures should be within +/- 2°C.

^ If the engine coolant temperature is still showing a hot or warm engine, the engine coolant temperature sensor has failed. Replace the engine thermostat.

2. If fault codes are stored:

^ Replace the engine thermostat.

Note:
If the ISTA system message displays: "Battery voltage only "XX.XX" V. Please connect charger", connect an approved charger and note the displayed battery voltage reading in the repair order comments section.





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