Input/Turbine Speed Sensor A Circuit

What it means

The input speed sensor measures the speed of the transmission input shaft after the torque converter. The computer uses it with output speed to calculate gear ratio and control shifts, and it has detected a fault in this sensor circuit.

Related codes: P0716P0717P0718P0720P0730

Symptoms4

• Check engine light on.
• Harsh, delayed or erratic shifts.
• Transmission in limp mode, stuck in one gear.
• Torque converter clutch not locking.

Possible causes5

• Damaged or corroded sensor connector, or fluid inside it.
• Open or shorted sensor wiring.
• A faulty sensor.
• Metal debris on a magnetic sensor tip on some designs.
• A fault in the transmission control module (rare).

How to diagnose5

1. Watch input speed on a scan tool while driving and compare it with engine speed when the converter clutch is locked.
2. Inspect the sensor connector and wiring for damage, fluid or rubbing.
3. Measure sensor resistance or supply voltage depending on its type, and compare with the manufacturer specification.
4. Check the sensor signal with an oscilloscope while the shaft turns, if possible.
5. Remove an external sensor and inspect its tip for debris or damage.

How to fix5

1. Clean the connector and repair damaged wiring.
2. Clean debris from the sensor tip and look for its source inside the transmission.
3. Replace the input speed sensor, which is inside the transmission on some designs.
4. Change the transmission fluid and filter if heavy debris is found.
5. Clear the codes and confirm the input speed reading appears and normal shifting returns.

The cost is low for a connector repair or an easy-to-reach external sensor, and higher when the sensor sits inside the transmission and needs the pan or valve body removed.

Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026

Frequently asked questions