AMG models with torque converter 725.0 (NAG3 Classic) and M177
engine - Harsh shift concerns due to speed sensor installation
Topic number

LI27.00-P-080462

Version

1

Function group

27.00 - General

Date

4/14/26

Validity

Affects all 167 with M177 engine and transmission
725.085 (NAG3 Classic w/ torque converter) produced as
of July 1, 2025
Older models with 725.085 (NAG3 Classic w/ torque converter) transmissions were NOT affected in production,
but may have received affected replacement parts (A725
270 55 09) during valve body replacement

Reason for change

Complaint
Harsh upshifts, downshifts, or jolting in lower gears when accelerating.

Attachments
File

Description

Valve body - ECU serial number and date code.jpg

Figure 2

EEPROM txt file - ECU date code.png

Figure 1

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Cause
Incorrectly installed (rotated) rotational speed sensors on the EHS (VGS Control Unit) can cause abnormalities in signals. As a result, poor adaptation values are stored and harsh gearshifts are felt.
This only affects vehicles with VGS control units produced between days 182-296 of 2025 (July 4, 2025-October 23,
2025).

Remedy
1. Collect initial transmission EEPROM file
2. Check EEPROM .txt file for VGS control unit serial number and production date (attachment figure 1)
- If the valve body is already removed, you can inspect the control unit for its stamped serial number (attachment figure 2)
If the production date is or is within 25182-25296 (07/4/25-10/23/25):
The complete valve body will require replacement.
1. Remove transmission oil pan & inspect fluid/pan/filter condition
- compare findings to extended fluid condition examples provided in Xentry blue book under general information for
VGS
2. Replace complete EHS valve body, fill to near max fluid level, & complete initial start-up
- Ensure all oil guide pipes are installed in the new valve body to prevent a new concern after replacement. (See photos in WIS instructions)
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- Verify the new valve body production date is outside of day 182-296 of 2025 (attachment figure 2)
If the production date is outside of this range:
This LI is not applicable.
1. Perform IPR and follow recommended instruction

Disclaimer
NOTE: The information contained in this document is intended for use by trained, professional technicians with the
knowledge to properly and safely perform diagnosis and repairs on Mercedes-Benz vehicles, using Mercedes-Benz
approved tools and equipment. It informs service technicians about conditions that could occur in certain vehicles and
provides information that could assist in proper vehicle diagnosis, service, or repair. It does not indicate that a defect
is present in any vehicle referenced in this document nor does it imply warranty coverage. DO NOT assume that a
symptom or condition, or a described cause of a symptom or condition, affects any particular vehicle or groups of vehicles, or that a described repair applies to any particular vehicle or groups of vehicles. There can be multiple causes
resulting in the same or similar symptoms or conditions described in this document, and trained professional service
technicians must use their diagnostic skills to make evaluations on a case-by-case basis. The information contained
in this document does not guarantee warranty coverage nor does it extend the vehicle’s warranty in any way.

Symptoms
Power transmission > Automatic transmission > Function > Shifts
Power transmission > Automatic transmission > Function > Poor shift quality

Parts
Part number

ES1 ES2 Designation

A725 270 55 09
87

Quantity Note

CONTROLLER UNIT, ELECTROH

1

EPC

Verify the new valve body production date is outside of day 182-296 of
2025 (attachment figure 2)

X

Operation numbers/damage codes
Op. no.

Operation text

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Time

SAHARRY

Damage
code

Note

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