P0718 Fault Code in Hyundai: Causes, Symptoms, and Fixes

P0718 is triggered when the Transmission Control Module (TCM) detects an intermittent or erratic signal from the Input/Turbine Speed Sensor A. This sensor monitors how fast the input shaft of the transmission is spinning and is critical for smooth shifting and torque converter operation.

Symptoms:

1. Check Engine Light (CEL)
2. Transmission slipping or shifting harshly
3. Delayed gear changes
4. Vehicle may go into limp mode
5. Inaccurate speed readings
6. Decreased fuel economy

Common Causes:

1. Loose or corroded electrical connector
2. Frayed, damaged, or shorted wiring
3. Failing input/turbine speed sensor
4. Poor ground connection
5. Moisture or oil contamination in the connector
6. TCM issues (less common)

Diagnostic Steps:

1. Scan live data to see if input speed fluctuates abnormally
2. Wiggle test the harness while monitoring data — if signal drops, wiring may be faulty
3. Visually inspect connectors and wiring for corrosion, fraying, or poor connections
4. Test sensor resistance and signal output using a multimeter
5. Check for loose grounds or blown fuses

Possible Fixes:

1. Clean or replace the sensor connector
2. Repair or replace damaged wiring
3. Replace the input/turbine speed sensor
4. Check and clean ground points
5. If problem persists, consider reprogramming or replacing the TCM