Engine-Codes - Mercedes-Benz - P0731 Mercedes-Benz

P0731 Mercedes-Benz Code - Gear 1 Incorrect Ratio

- Code Popularity: 14,464 Views
- Repair Importance Level: 3/3
- Repair Difficulty Level: 3/3
Table of contents
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What are the Possible Causes of the DTC P0731 Mercedes-Benz?

NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
  • Low transmission fluid level
  • Dirty transmission fluid
  • Shift solenoids
  • Transmission mechanical problems
  • Transmission hydraulic control circuit

Code Tech Notes

Start by inspecting the transmission fluid level and condition, and change fluid if necessary.

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How to Fix the DTC P0731 Mercedes-Benz?

Check 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 pins.

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What is the Cost to Diagnose the Code?

Labor: 1.0

The cost to diagnose the P0731 Mercedes-Benz code is 1.0 hour of labor. The diagnosis time and labor rates at auto repair shops vary depending on the location, make and model of the vehicle, and even the engine type. Most auto repair shops charge between $75 and $150 per hour.

When is the Code Detected?

P0731 is detected when A/T cannot be shifted to the 1st gear position even if electrical circuit is good.

What are Code Possible Symptoms?

  • Engine Light ON (or Service Engine Soon Warning Light)
  • Incorrect transmission shifting

What Does the P0731 Mercedes-Benz Code Mean?

This diagnosis monitors actual gear position by checking the torque converter slip ratio calculated by Transmission Control Module (TCM) as follows:

Torque converter slip ratio = A x C/B
A: Output shaft revolution signal from revolution sensor
B: Engine speed signal from Engine Control Module (ECM)
C: Gear ratio determined as gear position which TCM supposes

If the actual gear position is higher than the position (1st) supposed by TCM, the slip ratio will be more than normal. In case the ratio exceeds the specified value, TCM judges this diagnosis malfunction.

P0731 Mercedes-Benz Code - Gear 1 Incorrect Ratio

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