Engine Controls - DME Code 2EF4/279B Diagnostics
SI B 12 15 05Engine Electrical Systems
April 2010
Technical Service
This Service Information bulletin supersedes SI B12 15 05 dated March 2008.
[NEW] designates changes to this revision
SUBJECT
N62 - Diagnosis of DME ME 9.2 Map Thermostat Fault 2EF4/279B
MODEL
E65, E66 with N62 from start of production up to 03/05
E60, E63, E64 with N62 from start of production up to 09/05
SITUATION
The "Service Engine Soon" lamp is illuminated. Fault code 2EF4 (279B) - "Map cooling thermostat mechanically stuck" is stored in the DME.
The engine does not overheat and the map thermostat operates properly.
CAUSE
Possible causes are:
^ Deterioration of coolant quality (the mixture concentration falls below 50%).
^ Increased contact resistance between the thermostat temperature sensor, the engine wiring harness and the DME connector.
^ Internal defect of a map cooling thermostat.
CORRECTION
On a customer complaint basis only, perform the applicable repair (production date dependent) as listed below:
1. On vehicles equipped with the N62B44 engine (DME ME 9.2.1/9.2.2) manufactured from 09/04 through 12/04 , replace the engine wiring harness and the temperature sensor.
2. On vehicles equipped with the N62B44 engine (DME ME 9.2.1/9.2.2) manufactured outside the above-specified production range [if the map cooling thermostat faults (279B or 4EF4) are stored]:
^ Check the coolant concentration. If the coolant/water mix falls below 50%, correct as needed.
^ Perform the appropriate ISTA/D test plan. Replace the map coolant thermostat when prompted by the test results.
^ If the vehicle returns to the workshop with the same complaint (Service Engine Soon illuminated and fault code 279B/2EF4 stored in DME) and the thermostat has already been replaced during the previous repair, it is highly unlikely that the map cooling thermostat failed again. The increased connection resistance would most likely cause the repeat failure. The engine wiring harness and temperature sensor should be replaced.
PARTS INFORMATION
WARRANTY INFORMATION