MERCEDES TSB: S-B-14.00/31: Notes

1. Model Year: All, Models: All 
2. I/M 240 Emissions Testing on Dynamometer 
3. The enhanced Inspection/Maintenance emission testing program (I/M 240) is in effect in several states.
4. It is recommended that all vehicles be tested on a 4-wheel dynamometer. 

The following vehicle may be tested on a 2-wheel dynamometer:

• Mercedes-Benz vehicles that are 2WD and not equipped with Acceleration Slip Regulation (ASR)
• Mercedes-Benz, Maybach and smart vehicles that are 2WD and have "Dyno-Mode" capability (must be activated)

The following vehicles must  be tested on a 4-wheel dynamometer:

• Mercedes-Benz vehicles equipped with ASR
• Mercedes-Benz vehicles equipped with 4MATIC
• Mercedes-Benz vehicles that are 2WD and do not have "Dyno-Mode" capability

1. Please see Attachment 1  (below) for a list of vehicles that must be tested on a 4-wheel dynamometer.
2. Please see Attachment 2  (below) for a list of vehicles with "Dyno-Mode" capability and the activation procedure.

According to US Environmental Protection Agency (EPA) procedures, if an emissions inspector has difficulty performing the I/M 240 test on a 2-wheel dynamometer, the following should be considered:

• Test the vehicle on a 4-wheel dynamometer, or
• Perform an optional emission test at idle +2500 rpm

An emissions inspector should also consider the options above if they are uncertain about the Dyno-Mode activation procedure or is uncertain about which vehicles can operate on a 2-wheel dynamometer.