What it means
The transmission input speed (turbine) sensor signal is missing or implausible. Without this signal, the TCM cannot detect torque converter slip or calculate gear ratio in real time, and shifts become harsh.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Input/turbine speed sensor A measures how quickly the transmission input shaft turns and sends that signal to the TCM. P0715 sets when the signal is missing or implausible, leaving the TCM without reliable input speed for monitoring converter slip and calculating gear ratios.
Common causes
Most likely first.
- Input speed sensor failed
- Wiring or connector fault
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
How to diagnose it
- Record freeze-frame data and compare input speed sensor A's reading with engine RPM and vehicle speed under the conditions when the code set.
- Inspect sensor A's connector and harness for loose pins, corrosion, damage, or wiring routed against hot or moving parts.
- Check the sensor circuit for opens, shorts, and poor continuity using the manufacturer's wiring information.
- Test sensor A's output with the manufacturer's specified method while the input shaft is turning, taking care to use the correct vehicle procedure.
- If the circuit and sensor pass, investigate the transmission's internal signal source or mechanical condition using vehicle-specific service information.
Common fixes
- Reconnect or clean sensor A's connector if contact is poor.
- Repair damaged wiring or connector faults in the input speed sensor A circuit.
- Replace input/turbine speed sensor A if it fails its specified output test.
- Repair an internal transmission fault if the sensor and its circuit work but the speed signal remains absent or implausible.
Can I keep driving?
Avoid towing, hard acceleration, and unnecessary trips because the transmission may shift harshly or enter limp mode. Stop if drive is lost or the transmission slips, and arrange prompt diagnosis.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.