P0715: The transmission cannot measure its input shaft speed
Input/Turbine Speed Sensor A Circuit Malfunction
The transmission input speed sensor signal is missing, so shifting may be harsh or stuck, or it may go into limp mode. Get it checked today. If it slips or will not shift, stop driving.
Stop driving and get help if
- The check engine light is flashing
- The temperature gauge runs high, or you see steam (overheating)
- The car loses power, hesitates badly or stalls
- You smell burning or see smoke
- A brake warning light comes on, or the brakes feel different
Pull over as soon as you can, turn the engine off, and call a tow or roadside help.
What it means
The input speed sensor measures how fast the transmission's input shaft is spinning. The TCM uses this data to calculate slip across the torque converter and to control shift timing and pressure. Without it, the transmission is operating blind on those calculations. P0715 means the signal from this sensor is missing or out of range. The sensor itself is the most common failure, but fluid contamination from a worn transmission can also destroy sensors quickly, so check fluid condition alongside the sensor.
Common causes
- Failed input speed sensorThe magnetic sensor wears or the tip breaks off from contact with the tone ring.
- Damaged or corroded wiring to the sensorLocated inside the transmission bellhousing area; wiring exposure varies by design.
- Contaminated or metal-particle-laden transmission fluidMetal debris from internal wear can damage the sensor or its tone ring.
- Damaged reluctor ring (tone wheel)The toothed ring the sensor reads can shed teeth or corrode.
What the fix could involve
From the cheaper fix to the bigger one. Prices depend on your car, your area and the shop, so ask for a written quote that names the part and the labor before you approve it.
- Input speed sensor replacement
- Transmission fluid and filter service
- Wiring repair
Symptoms
- Harsh or erratic shifting
- Transmission limp mode
- Torque converter clutch will not lock up
- Speedometer inaccurate in some vehicles
- Check engine and transmission warning lights
What to do next
Check the transmission fluid level and condition first. If it is dark, burned, or has metal particles in it, the transmission has internal wear and replacing only the sensor will not address the underlying damage. If fluid is in good condition, the sensor itself or its wiring is the likely fix.
Lewis shows live vehicle speed and RPM alongside P0715 and any related speed sensor codes, so you can see whether the other speed signals are healthy. Get Lewis on the App Store or Google Play.
Related codes
FAQ
- Can I drive in limp mode to the dealer?
- Limp mode typically locks you into second or third gear. It is there to protect the transmission, not for normal driving. Stay off highways, get it checked today, and have it towed if it slips or will not shift.
- Is the sensor accessible without dropping the transmission?
- On most vehicles, yes. Input speed sensors are typically on the outside of the transmission case. Some require removal of a bellhousing cover.
- Should I change the transmission fluid at the same time?
- Yes, especially if it has not been changed recently. Metal contamination in the fluid damages sensors and valves.
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