P0715: Input/Turbine Shaft Speed Sensor A Circuit
What to do
The transmission has most likely dropped into a single fixed gear to protect itself, which is meant to get you home rather than to be driven on — an unlocked converter puts heat into fluid the cooler was not sized to handle. Keep the journey short.
What this code means
The sensor reporting the speed of the transmission's input shaft is not sending a usable signal. This is the single most important measurement the transmission module takes, because almost everything it concludes rests on comparing two speeds.
Input speed against output speed gives the ratio actually being achieved, which is how the module knows which gear is really engaged rather than which one it asked for — the whole P0730 family of gear ratio codes is built on that comparison. Input speed against engine speed gives the slip across the torque converter, which is how lock-up is verified. Lose the input signal and the module can no longer check either, so it stops trusting its own shift scheduling and defaults to a fixed gear.
On many transmissions this sensor is inside the case, which raises the cost of the job considerably and makes it worth being certain before committing: confirm the signal is absent at the module rather than at the sensor alone, since a harness fault costs a fraction of the same repair.
Likely causes
Start here
- Faulty turbine speed sensor · specialist
- Damaged transmission wiring harness · moderate
- Corroded transmission connector · moderate
Less common
- Metal debris on the sensor tip · specialist
- Low or degraded transmission fluid · easy
Rare
- Faulty transmission control module · specialist
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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