P0715: OBD-II code P0715 flags a fault in the input/turbine speed sensor circuit — the TCM can't measure torque converter turbine speed for slip calculation.

Symptoms

• Check engine light is on; the transmission may shift harshly, hold gears too long, or enter limp mode.
• TCC lock-up may be erratic because slip can't be measured accurately without turbine speed data.
• Speedometer may be unaffected but transmission behaviour degrades noticeably.

Common causes

• A failed input speed sensor with intermittent output or drifting signal.
• Damaged wiring or a corroded connector at the sensor on the transmission case.
• Metallic debris on the sensor tip from internal clutch wear inside the transmission.

What to do?

Read live input speed data during a road test. Test the sensor with a scan tool. Replace the sensor if it's faulty. Change the transmission fluid and filter if metallic debris is found on the sensor tip during replacement.