AutoCodes – Audi – P0731 Audi

P0731 Audi Code - Gear 1 Incorrect Ratio

Quick Answer

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. Common causes include Low transmission fluid level, Dirty transmission fluid, Shift solenoids. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P0731 Audi indicates Gear 1 Incorrect Ratio.
Common causes: Common causes include Low transmission fluid level, Dirty transmission fluid, Shift solenoids.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 8,975

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jun 14, 2020

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0731 Audi Description

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.

OBDII Code P0731 Audi - Gear 1 Incorrect Ratio - AutoCodes.com — P0731 Audi Code - Gear 1 Incorrect Ratio

What does this mean?

What are the Possible Causes of the DTC P0731 Audi?

Low transmission fluid level
Dirty transmission fluid
Shift solenoids
Transmission mechanical problems
Transmission hydraulic control circuit

How to Fix the DTC P0731 Audi?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

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

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0731 Audi code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0731 Audi Code

1. What does the OBDII code P0731 mean for an Audi?

P0731 indicates "Gear 1 Incorrect Ratio," meaning the transmission's gear ratio in first gear is not matching the expected value.

2. What are common symptoms of the P0731 code in an Audi?

Symptoms may include slipping in first gear, delayed shifting, harsh gear changes, reduced acceleration, or the check engine light being illuminated.

3. What causes the P0731 code in an Audi?

Common causes include low transmission fluid, a faulty transmission control module, damaged gear components, or issues with the torque converter.

4. Can low transmission fluid cause the P0731 code?

Yes, insufficient or degraded transmission fluid can lead to improper gear engagement and trigger the P0731 code.

5. How do you diagnose the P0731 code on an Audi?

Diagnosis involves checking transmission fluid levels, inspecting wiring and connectors, scanning for related codes, and testing the transmission control module and internal components.

6. Can driving with the P0731 code damage the transmission?

Yes, prolonged driving with this code can cause further damage to the transmission, especially if gear slippage or overheating occurs.

7. How do you fix the P0731 code on an Audi?

Repairs may include refilling or replacing transmission fluid, repairing wiring issues, replacing damaged gear components, or reprogramming the transmission control module.

8. Is it expensive to fix the P0731 code on an Audi?

The cost varies depending on the cause, ranging from a simple fluid change to transmission repair or replacement, which can be costly.

9. Can a faulty transmission solenoid cause the P0731 code?

Yes, a malfunctioning solenoid can prevent proper gear engagement, leading to an incorrect ratio in first gear.

10. Should the transmission be replaced if the P0731 code appears?

Not necessarily. Many P0731 issues can be resolved by addressing specific components, but severe internal damage may require transmission replacement.