Tech Tip: Mercedes-Benz ESP Warning Lamp On/Multiple DTCs Set – UnderhoodService

Tech Tip: Mercedes-Benz ESP Warning Lamp On/Multiple DTCs Set

Models affected: 163.113/128/154/157/175 VIN range as of 371935 up to 442083 with ESP control unit MK25

If you receive customer reports in the above models of the Electronic Stability Control (ESP) warning lamp being illuminated with the following stored fault codes (listed below), perform the following ­repair procedure.
• C1140 – B34 ESP Brake Pressure Sensor (Electrical Fault)
• C1145 – Zero Point Offset Error of Component B34 (ESP Brake Pressure Sensor)
• C1185 – A7/7b1 BAS ­Diaphragm Travel Sensor (Electrical Fault)
• C1186 – A7/7b1 BAS ­Diaphragm Travel Sensor (Zero Point Variation)
• C1187 – A7/7b1 BAS ­Diaphragm Travel Sensor (Open Circuit)

Note: Do not replace the ESP control unit.
Note: ESP lamp illumination may be the result of increased resistance on the terminals within the connector for the ESP control unit (N47-5) due to oxidation.

1. Repair the wiring harness connector on the ESP control module. 

2. If any of the above fault codes are current, perform a diagnostic test on the brake pressure sensor (B34/2) and/or brake booster piston travel sensor (A7/7b1) using STAR Diagnosis.

3. If the brake pressure sensor (B34/2) is found to be faulty, ­replace it. Reference WIS document AR42.45-P-0816GH.

4. If the brake booster piston travel sensor (A7/7b1) is found to be faulty, replace it. Reference WIS document AR42.31-P-6002GI.

Courtesy of Identifix.

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