The P0791 OBD-II trouble code indicates an issue with the Intermediate Shaft Speed Sensor “A” Circuit. This code is serious as it can affect vehicle performance significantly.
What Does the P0791 Code Mean?
When the P0791 code is triggered, it means that the Transmission Control Module (TCM) is receiving an inaccurate signal from the Intermediate Shaft Speed Sensor. This sensor is crucial for determining the speed of the intermediate shaft in the transmission, allowing the TCM to select the appropriate gear for the vehicle’s speed and acceleration needs.
What Causes the P0791 Code?
Several factors can lead to the P0791 code being set, including:
- Intermediate shaft speed sensor failure
- Powertrain Control Module (PCM) failure
- Transmission Control Module (TCM) failure
- Wiring issues, such as damaged or corroded wires
What Are the Symptoms of the P0791 Code?
When the P0791 code is present, you may experience the following symptoms:
- Transmission may not shift properly
- Increased fuel consumption
How Serious Is the P0791 Code?
The P0791 code is considered urgent. It indicates a significant malfunction that can lead to severe damage to the vehicle’s transmission if not addressed promptly. Delaying repairs can put both the vehicle and its occupants at risk.
How to Diagnose the P0791 Code
Diagnosing the P0791 code involves several steps:
- Use an OBD-II scanner to confirm the code and check for any other related trouble codes.
- Inspect the Intermediate Shaft Speed Sensor and its wiring for any visible damage or corrosion.
- Test the sensor’s voltage and resistance according to the manufacturer’s specifications.
- Check the functionality of the PCM and TCM if no issues are found with the sensor.
Common Repairs for the P0791 Code
Repairs for the P0791 code may include:
- Replacing the Intermediate Shaft Speed Sensor
- Repairing or replacing damaged wiring and connectors
- Reprogramming or replacing the PCM or TCM if they are found to be faulty
How Much Does It Cost to Fix the P0791 Code?
The cost to fix the P0791 code can vary significantly depending on the specific issue. Typically, you might expect to pay:
- Sensor replacement: $100 – $300
- Wiring repairs: $50 – $200
- PCM/TCM replacement: $500 – $1,500
Can I Fix the P0791 Code Myself?
While some DIY enthusiasts may be able to replace the Intermediate Shaft Speed Sensor or inspect wiring, diagnosing and fixing the P0791 code can be complex. If you’re not experienced with automotive repairs, it’s advisable to seek professional help to ensure the problem is resolved correctly.
