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

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

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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.

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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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