Modern car transmissions are incredibly complex. So much so that they have dedicated computers that control them. These computers rely on a bunch of sensors in the transmission to monitor what’s going on with the system. When one of the sensors fails, or when the transmission isn’t operating as intended, you’ll get a check engine light code to pop up.
One of the codes you can find is the P0715 fault code that’s triggered when the transmission control module detects a faulty signal from the input/turbine speed sensor. This sensor is essential for the transmission to work properly and provide you with the driving experience you’re expecting.
In this article, we’ll go into detail about the P0715 code, what the turbine sensor does, where it’s located, the causes of the P0715 fault code, how to diagnose it, and how to fix it.
What Is The P0715 Code, And What Does It Mean?
The P0715 fault code stands for input/turbine speed sensor circuit. To put it in simple words, it means that the car’s ECU has detected an irregular signal coming from the input/turbine speed sensor located in the transmission.
This sensor measures the number of revolutions per minute of the input shaft in the transmission. When the sensor sends faulty readings to the ECU or TCM, most cars engage a fail-safe (or limp-mode as some call it) mode, limiting the speed and power of the car to prevent further damage to the transmission.
What Does The Turbine Speed Sensor Do?
The turbine speed sensor is used to measure the RPM of the transmission’s input shaft. These readings directly affect the vehicle’s performance making the turbine speed sensor one of the most crucial sensors in the transmission.
By reading the transmission’s input shaft RPM, the ECU or TCM detects the correct gear change timing and adjusts torque and hydraulic pressure depending on the conditions. When the sensor is working properly, your car will provide optimal performance and economy. Gear changes will also be smooth.
Where Is The Input Turbine Speed Sensor Located?
The input turbine speed sensor is located in most vehicles on the transmission itself, or inside it. It’s pretty difficult to reach, especially if it’s located on top of the transmission housing. This means that you’ll need to remove the transmission to access it or even disassemble it if it’s located inside of the transmission.
What Causes A P0715
A couple of things can cause the P0715 code which includes a faulty input/turbine speed sensor, damaged wiring, debris on the sensor, and a damaged reluctor ring on the transmission for the input/turbine speed sensor.
Faulty Input/Turbine Speed Sensor
A faulty input/turbine speed sensor is the first thing many people think of when they encounter the P0715 code. Unfortunately, it’s not the only thing that can cause the P0715 fault code.
When the input speed sensor is faulty, it’s expected that it will send false information to the TCM or ECU which will eventually end up triggering the P0715 fault code.
Damaged Wiring
Damaged wiring is a common cause for a lot of generic fault codes, and it’s the same with the P0715 code as well. Damaged wiring can lead to the sensor sending either false information to the ECU or not sending readings at all. Amongst others, this can trigger the P0715 code as well.
Debris
The input speed sensor should be sealed properly, but debris can reach the sensor nonetheless. The debris can reach the sensor from within the transmission, but it can also reach it from outside, as well. Debris from the transmission blocks the sensor due to improper transmission maintenance and when the small magnet isn’t strong enough to hold the metal particles in place. Debris from the outside can also reach the sensor if the housing isn’t sealed properly.
Damaged Reluctor Ring
Another common cause for the P0715 fault code is a damaged reluctor ring on the transmission shaft. The input speed sensor gets information about the RPM directly from the reluctor ring, so if it’s damaged, the sensor won’t have an accurate reading and will send false information to the ECU. Even the smallest damage on the reluctor ring will cause the P0715 code.
Common Symptoms Of The P0715 Code
When it comes to the symptoms to look for when suspecting the P0715 code, they’re different depending on the make and model of your car, but some of the most common symptoms include the check engine light, lack of power, unable to shift gears, stalling when braking to a stop, false speedometer reading, decreased fuel economy.
The check engine light is a common symptom not just for the P0715 fault code, but for any fault code stored in the ECU. It just means there’s an issue present and should be checked out as soon as possible.
The lack of power is a direct response of the vehicle to the P0715 code. Most vehicles will enter a fail-safe mode when the ECU detects an issue with the input/turbine speed sensor to prevent further damage from occurring.
Depending on the issue, some cars will be unable to shift gears and will be stuck in one gear. This also means that the car will likely stall when you try to bring it to a full stop.
False speedometer readings are common especially because the information from the transmission shaft is used in some cars to calculate the current speed. If the sensor sends uneven readings, the speedometer will show different speeds even though you’re driving at a steady pace.
How To Diagnose And Fix P0715 Code
Diagnosing the P0715 fault code starts with doing two things – checking the stored codes in the ECU with an OBD II scanner, and checking the technical service bulletins for your car. Having as much information as possible before diagnosing a specific issue can save you time and money.
If the P0715 code is the only one stored in the ECU, the next thing you should do is inspect the wiring. You can do this either with a multimeter or by visually checking the wires and connectors. Also, check for leaks because fluids can damage and corrosion to the wiring and connectors. If you notice any damage or corrosion on the wiring or connectors, you’ll need to replace the affected part with a new one.
If the wiring and connectors look good, you’ll need to remove the input speed sensor and check for debris. If present, it will be clearly visible on the sensor. Depending on how much debris you found on the sensor, just cleaning it could solve the issue, but if there’s a larger buildup of metal particles on the sensor, there might be internal damage in the transmission itself. At this point, you should also visually inspect the reluctor ring inside the transmission. If it’s not in good condition, it should be replaced as well.
Lastly, if the code returns, you’ll need to check the resistance of the input/turbine speed sensor with a multimeter. If it returns faulty readings, replacing the sensor with a genuine OEM part will solve the P0715 code.
Can You Drive With A P0715 Code?
The P0715 fault code is considered extremely severe, and aside from preventing the car from driving normally, it can lead to additional damage to the transmission. If you encounter this fault code, you shouldn’t drive the car until the issue is resolved.
Always Use Genuine Parts When Dealing With The P0715 Code
We already mentioned how important the input/turbine speed sensor is, which only tells you that high-quality parts should be used for repairs. Although affordable alternatives are available on the market, the savings won’t be worth it once the same issue comes back after a few months. That’s why we at eEuroparts.com offer only Genuine, OEM or high-quality aftermarket alternatives that provide reliable performance and functionality.
Our vehicle selection tool is a very handy tool when searching for specific parts. By selecting the specific year, make and model, you’ll find only parts that are made specifically for your vehicle. This will reduce the time required for finding parts and reordering if a certain part doesn’t fit your vehicle.
