What is OBD-II Code P07BF – Input/Turbine Shaft Speed Sensor A Circuit Low
If you have a car that was manufactured after 1996, chances are you have an onboard diagnostic system, which is also known as the OBD system. The OBD-II system provides several benefits to car owners, including monitoring the emission levels and detecting any issues within the vehicle. However, if there’s something wrong with your car, the OBD-II system will generate a code, which can be confusing if you don’t know what the code means. In this article, we will be discussing OBD-II Code P07BF – Input/Turbine Shaft Speed Sensor A Circuit Low, what it means, and how to fix it.
What is OBD-II Code P07BF?
OBD-II Code P07BF is a diagnostic trouble code that indicates a malfunction in Input (Turbine) Shaft Speed Sensor A Circuit Low. Input Shaft Speed (ISS) Sensor “A” Circuit Low is the technical description for this code. This code indicates that the Input Shaft Speed (ISS) Sensor A detected a low voltage. The Input Shaft Speed Sensor measures the speed of the input shaft to the transmission to determine shift strategy and TCC strategy. The engine control module (ECM) utilizes this speed signal to control transmission shift points as well as TCC apply and release.
What are the Symptoms of OBD-II Code P07BF?
When the OBD-II Code P07BF appears, you may experience a variety of symptoms concerning the transmission. For starters, the Transmission Control Module (TCM) may set the transmission into a “limp-in” mode that will usually only allow you to use second and third gear. Furthermore, the vehicle may not shift gears properly, and the transmission may slip. You may also notice that the transmission runs hotter than usual. Depending on the specific transmission that your vehicle has, some possible symptoms that you may notice include:
– Harsh shifting
– Transmission overheating
– Slipping transmission
– Vehicle enter’s limp mode or goes into a default gear ratio
What are the Causes of OBD-II Code P07BF?
There are various reasons why the OBD-II Code P07BF may appear. Here are some of the most common reasons:
1. Code P07BF may be set when the Input Shaft Speed Sensor circuits are malfunctioning or when the ISS is faulty.
2. Wiring problems in the ISS circuit may also set P07BF.
3. If the Transmission Control Module (TCM) itself is malfunctioning, it may set P07BF.
4. Finally, a problem with the transmission may set P07BF.
How to Diagnose the Problem for OBD-II Code P07BF?
The first step in diagnosing the problem is to inspect and test the Input Shaft Speed (ISS) sensor circuit. The sensor can be accessed from beneath the vehicle, and it usually has two wires. Check the sensor’s wiring for any cuts, breaks, or shorts. Bear in mind that this sensor is frequently located close to the transmission’s oil pan, making it more vulnerable to damage.
After inspecting the wiring, you should test the sensor’s voltage signal, which should be between 0.3-1V. To do so, use a multimode digital voltmeter. Start the vehicle and place one lead on the sensor’s negative terminal and the other lead on the sensor’s signal terminal. Observe the voltage readings while the engine is running. If the sensor’s voltage signal is out of range, then it should be replaced. Finally, check the resistance of the sensor by calibrating it against the manufacturer’s specifications.
How to Fix OBD-II Code P07BF?
To fix OBD-II Code P07BF, you may need to do the following procedures:
1. Replace the Input Shaft Speed Sensor – If the problem lies in the Input Shaft Speed Sensor, then you need to replace it.
2. Replace Wiring Harness – If the wiring harness is damaged, you should replace it.
3. Replace TCM – If the TCM is malfunctioning, then you need to replace it.
4. Replace Transmission – If none of the above solutions work, you may need to replace the transmission.
Frequently Asked Questions (FAQs)
Q1. What is an OBD system?
Ans. OBD stands for On-Board Diagnostics. It’s a system that monitors the vehicle’s emissions and fixes issues within the vehicle through a computer system.
Q2. What is the Input Shaft Speed Sensor?
Ans. The Input Shaft Speed Sensor measures the speed of the input shaft to the transmission to determine shift strategy and TCC strategy. The engine control module (ECM) utilizes this speed signal to control the transmission shift points as well as TCC apply and release.
Q3. What does OBD-II Code P07BF mean?
Ans. It means that the Input Shaft Speed (ISS) Sensor A detected a low voltage. The Transmission Control Module (TCM) may set the transmission into a “limp-in” mode, and the vehicle may not shift gears properly.
Q4. How can I diagnose the problem with OBD-II Code P07BF?
Ans. The first step is to inspect and test the Input Shaft Speed (ISS) sensor circuit. Check the sensor’s wiring for any cuts, breaks, or shorts. Finally, test the sensor’s voltage signal, which should be between 0.3-1V. Observe the voltage readings while the engine is running.
Q5. How to fix OBD-II Code P07BF?
Ans. To fix OBD-II Code P07BF, you may need to replace the Input Shaft Speed Sensor, wiring harness, TCM, or even the transmission.
Conclusion
OBD-II Code P07BF is a diagnostic trouble code that indicates a malfunction in Input (Turbine) Shaft Speed Sensor A Circuit Low. This code could be set due to various reasons, including the Input Shaft Speed Sensor circuits malfunctioning, wiring problems, a faulty or malfunctioning TCM, or even a transmission problem. As a car owner, it’s essential to diagnose the issue and fix it as soon as possible to prevent further damage to your vehicle. Inspect the ISS first and then check the voltage signal. If necessary, replace the ISS and/or the wiring harness. If none of the above solutions work, you may need to replace the TCM or even the entire transmission.