P0791 Scion Code - Intermediate Shaft Speed Sensor 'A' Circuit
Quick Answer
This sensor detects the rotation speed of the counter gear which indicates the output speed of the transaxle. Common causes include Faulty Speed sensor NC (Transmission Revolution Sensor), Speed sensor NC harness is open or shorted, Speed sensor NC circuit poor electrical connection. 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 Scion indicates Intermediate Shaft Speed Sensor 'A' Circuit.
- Common causes
- Common causes include Faulty Speed sensor NC (Transmission Revolution Sensor), Speed sensor NC harness is open or shorted, Speed sensor NC circuit poor electrical connection.
- 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.
Code P0791 Scion Description
The NT terminal of the ECM detects a pulse signal from the speed sensor NT (input RPM). The ECM calculates gear shifts by comparing the signal from speed sensor NT with the signal from speed sensor NC.
While the vehicle is operating in 2nd, 3rd, 4th, or 5th gear with the shift lever in D, if the input shaft speed is less than 300 rpm although the output shaft speed is more than 1000 rpm, the ECM interprets this as a fault, illuminates the MIL and stores the Diagnostic Trouble Code (DTC). 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.
What are the Possible Causes of the DTC P0791 Scion?
- Faulty Speed sensor NC (Transmission Revolution Sensor)
- Speed sensor NC harness is open or shorted
- Speed sensor NC circuit poor electrical connection
- Faulty Engine Control Module (ECM)
How to Fix the DTC P0791 Scion?
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 is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P0791 Scion 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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Frequently Asked Questions about P0791 Scion Code
What does the OBDII code P0791 mean on a Scion?
P0791 indicates an issue with the Intermediate Shaft Speed Sensor 'A' Circuit, which monitors the rotational speed of the transmission's intermediate shaft for proper gear shifting.
What are common symptoms of the P0791 code on a Scion?
Common symptoms include erratic or delayed shifting, transmission slipping, poor fuel economy, and illumination of the check engine light.
What causes the P0791 code on a Scion?
Possible causes include a faulty intermediate shaft speed sensor, damaged wiring or connectors in the sensor circuit, or issues with the transmission control module (TCM).
Can a dirty or damaged speed sensor trigger the P0791 code?
Yes, dirt, debris, or physical damage to the intermediate shaft speed sensor can prevent it from functioning correctly and trigger the P0791 code.
How do I diagnose the P0791 code on a Scion?
Start by inspecting the wiring and connectors of the speed sensor for damage or corrosion. Use a scan tool to check live data and verify the sensor's readings and operation.
Can driving with the P0791 code damage my Scion's transmission?
Yes, ignoring this code can lead to improper transmission operation, which may cause increased wear or potential damage over time.
How can I fix the P0791 code on a Scion?
Repairs may involve replacing the intermediate shaft speed sensor, repairing or replacing damaged wiring, or reprogramming the transmission control module.
Is the P0791 code specific to Scion vehicles?
No, the P0791 code can appear on other vehicles with OBDII systems, but the exact diagnosis and repair steps may vary by make and model.
Does a faulty transmission control module cause the P0791 code?
Yes, a malfunctioning transmission control module can fail to process the speed sensor data correctly, which may result in this code.
What tools are needed to resolve the P0791 code on a Scion?
You’ll typically need an OBDII scanner, multimeter, and possibly basic hand tools to inspect wiring, test the sensor, and clear the code.
Discuss the causes and fixes for P0791 Scion OBDII Code
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