Engine-Codes - Mercedes-benz - P0742 MERCEDES-BENZ

P0742 MERCEDES-BENZ Code - Torque Converter Clutch Circuit Stuck On

Repair Importance Level: 3/3
Repair Difficulty Level: 3/3
Table of contents

|P0742 MERCEDES-BENZ code possible causes

  • Low transmission fluid level
  • Dirty transmission fluid
  • Faulty torque converter clutch solenoid valve
  • Torque converter clutch solenoid valve harness or connectors
  • Torque converter clutch solenoid valve circuit is open or shorted
  • Transmission internal mechanical problem

|How is the P0742 MERCEDES-BENZ code repair?

Start by checking the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector's pins.

|P0742 MERCEDES-BENZ code tech notes

When the a transmission solenoid is stuck on, in most cases the problem is not the electrical part of the solenoid; the problem is foreign material obstructing the mechanical function of the solenoid or the flow of the fluid through the transmission valve body. If the transmission fluid is very dirty, it is recommend changing the transmission fluid and if possible removing the transmission pan for further diagnosis. Excessive debris or metal particles on the transmission pan could be an indication that there is a transmission mechanical failure and that the transmission will need to be rebuilt or replaced.

|What is the cost to diagnose the P0742 MERCEDES-BENZ code

Labor: 1.0

The cost to diagnose the P0742 MERCEDES-BENZ code is 1.0 hour of labor. The auto repair's diagnosis time and labor rates vary by location, vehicle's make and model, and even your engine type. Most auto repair shops charge between $75 and $150 per hour.

|When is the P0742 MERCEDES-BENZ code detected?

The Transmission Control Module (TCM) has detected slippage on the Torque Converter Clutch (TCC) during a period when the converter is commanded off

|What are P0742 MERCEDES-BENZ code possible symptoms?

  • Engine Light ON (or Service Engine Soon Warning Light)

|What is P0742 MERCEDES-BENZ code meaning?

The Torque Converter Clutch (TCC) solenoid valve is activated, with the gear in D4, by the Transmission Control Module (TCM) in response to signals sent from the vehicle speed and the Engine Control Module (ECM). Lock-up piston operation will then be controlled. When the torque converter clutch solenoid valve is activated, the torque converter lockup clutch will engage creating a 1 to 1 RPM ratio between the transmission input shaft and the rotational speed of the torque converter.
Lock-up operation, however, is prohibited when A/T fluid temperature is too low.
When the accelerator pedal is depressed (less than 2/8) in lock-up condition, the engine speed should not change abruptly. If there is a big jump in engine speed, there is no lock-up.

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