The 2021 Chevrolet Equinox triggering P0715 indicates a problem with the input/turbine speed sensor circuit. This compact SUV's 9-speed automatic transmission relies on this sensor for proper shift timing and torque converter control.
Understanding P0715
P0715 sets when the transmission control module detects a malfunction in the input speed sensor circuit. This sensor measures transmission input shaft speed (turbine speed), essential data for calculating shift points and detecting slip.
Input Speed Sensor Function
The input speed sensor reads the rotational speed of the transmission input shaft—the shaft connected to the torque converter turbine. The TCM compares this to engine RPM and output shaft speed to determine shift timing and torque converter clutch operation.
Symptoms of Failure
Without accurate input speed data, the transmission may shift erratically, exhibit harsh shifts, or enter limp mode. The speedometer may work normally (it uses output speed) while internal transmission operation suffers.
Common Causes
Sensor element failure. Contamination from metallic debris in transmission fluid. Damaged sensor connector or wiring. TCM circuit failure (less common). Physical damage to sensor or tone ring.
Diagnosis Procedure
Monitor sensor signal during operation—it should vary smoothly with input shaft speed. Check sensor resistance if accessible. Inspect connector for contamination or damage. Check fluid for debris indicating internal transmission wear.
Repair Costs
Input speed sensor replacement costs $200-500 depending on accessibility. Transmission fluid service during repair adds $150-250. If internal damage caused sensor issues, transmission repairs increase significantly.