Engine-CodesMazda – P0791 Mazda

P0791 Mazda Code - Intermediate Shaft Speed Sensor 'A' Circuit

Quick Answer

The P0791 code for Mazda vehicles indicates a problem with the Intermediate Shaft Speed Sensor 'A' Circuit. Common causes include Faulty intermediate shaft speed sensor, Wiring or connector issues related to the sensor, Transmission fluid contamination. 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
P0791 Mazda indicates Intermediate Shaft Speed Sensor 'A' Circuit.
Common causes
Common causes include Faulty intermediate shaft speed sensor, Wiring or connector issues related to the sensor, Transmission fluid contamination.
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.
Table of contents Created and updated by William Orellana on Sep 06, 2024
💬 Need more help? Ask Auto Expert for instant answers — it's free!
AutoCodes App

Fix Your Car Smarter

Try the New AutoCodes App!

Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.

AutoCodes App on Google Play

Code P0791 Mazda Description

The P0791 code for Mazda vehicles indicates a problem with the Intermediate Shaft Speed Sensor 'A' Circuit. This sensor is responsible for monitoring the speed of the intermediate shaft in the transmission. When this sensor malfunctions or fails, it can lead to issues with the vehicle's shifting behavior, causing erratic or harsh shifting, transmission slippage, or even the transmission going into limp mode. It is essential to address this issue promptly to prevent further damage to the transmission system.

OBDII Code P0791 Mazda - Intermediate Shaft Speed Sensor 'A' Circuit
P0791 Mazda Code - Intermediate Shaft Speed Sensor 'A' Circuit

Common Causes of P0791 Mazda

  1. Faulty intermediate shaft speed sensor
  2. Wiring or connector issues related to the sensor
  3. Transmission fluid contamination
  4. Transmission control module (TCM) malfunction
  5. Mechanical issues within the transmission

Symptoms of P0791 Mazda

  1. Erratic or harsh shifting
  2. Transmission slippage
  3. Transmission going into limp mode
  4. Check Engine Light illuminated
  5. Decreased fuel efficiency

How to Fix P0791 Mazda

  1. Diagnose the exact cause of the issue by using a scan tool to read the fault codes and testing the intermediate shaft speed sensor.
  2. Inspect the wiring and connectors associated with the sensor for any damage or corrosion, repairing or replacing as necessary.
  3. Check the transmission fluid for contamination or low levels, performing a fluid flush and refill if needed.
  4. Test the transmission control module (TCM) for any faults and reprogram or replace if necessary.
  5. If mechanical issues are suspected, such as worn-out components in the transmission, consider a professional transmission rebuild or replacement.

Cost to Fix P0791 Mazda

The typical repair costs for addressing the P0791 code in a Mazda vehicle can range from $150 to $500, depending on the extent of the issue and the required repairs. This estimate includes the cost of parts (such as a new intermediate shaft speed sensor or wiring harness) and labor. However, it's essential to note that actual costs may vary based on location, the specific model of Mazda, and the labor rates charged by the auto repair shop. It is recommended to obtain quotes from multiple shops to compare prices and ensure a fair price for the repair.

When is the Code Detected?

P0791 code is detected when the input speed sensor voltage is more than 1.9V or less than 0.1V for 2 seconds or more

Need more information about the P0791 Mazda code?

Need more information on how to fix the P0791 Mazda code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0791 Mazda code diagnosed by a professional: Find a repair shop in your area

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 P0791 Mazda Code

1. What does the OBDII code P0791 mean for a Mazda?

P0791 indicates an issue with the Intermediate Shaft Speed Sensor 'A' circuit, which monitors the rotational speed of the intermediate shaft to help control transmission operation.

2. What are the common symptoms of a P0791 code in a Mazda?

Symptoms may include erratic or delayed shifting, the transmission stuck in one gear, the check engine light illuminated, and reduced fuel efficiency.

3. What causes the P0791 code to trigger in a Mazda?

Common causes include a faulty intermediate shaft speed sensor, damaged wiring or connectors, transmission fluid issues, or a malfunctioning transmission control module (TCM).

4. Can I drive my Mazda with a P0791 code?

Driving with a P0791 code is not recommended as it can cause transmission performance issues and potential damage if left unresolved.

5. How do I diagnose a P0791 code in my Mazda?

Diagnosis typically involves checking the speed sensor and its wiring, testing the sensor's signal with a multimeter, inspecting the transmission fluid, and scanning for additional codes.

6. How is a P0791 code fixed in a Mazda?

Repairs may involve replacing the intermediate shaft speed sensor, repairing or replacing damaged wiring, flushing and refilling the transmission fluid, or reprogramming the TCM.

7. How much does it cost to repair a P0791 code in a Mazda?

The cost can vary depending on the exact issue, but replacing a speed sensor typically ranges from $150 to $400, including parts and labor.

8. Can low transmission fluid cause a P0791 code in a Mazda?

Yes, low or dirty transmission fluid can lead to sensor issues or poor transmission performance, potentially triggering the P0791 code.

9. What tools are needed to troubleshoot a P0791 code in a Mazda?

Common tools include an OBDII scanner, a multimeter, and basic hand tools for inspecting and replacing components.

10. Does the P0791 code always mean the speed sensor is faulty in a Mazda?

No, the code can also be caused by wiring issues, problems with the TCM, or even transmission fluid problems, so a thorough diagnosis is necessary.

Discuss the causes and fixes for P0791 Mazda OBDII Code

Code P0791 Mazda comments

No comments found for this page.