Input/Turbine Speed Sensor Circuit Intermittent
What does this mean?
Code P0718 indicates a problem with the transmission input/turbine speed sensor.
Disclaimer: This diagnostic code is part of the standard OBD2 system and can apply to Subaru Impreza models manufactured from 1996 to 2026. However, please note that the presence of this specific code depends on your vehicle's exact engine configuration, options, and production year.
Common Causes
Faulty input/turbine speed sensor
Low, dirty, or burnt transmission fluid
Damaged, chafed, or broken wiring harness
Symptoms to Watch For
- Check Engine Light is illuminated
- Transmission slipping between gears
- Hard or harsh gear shifting
- Transmission stuck in one gear
How to Diagnose
Common Solutions
**Repair or Replace Damaged Wiring/Connectors:** If the diagnostic steps identify chafed wires, corroded terminals, or a faulty connector, the primary fix is to repair the damaged section of the wiring harness or replace the connector. Use proper soldering techniques with heat-shrink tubing for wire repairs, or OEM-style crimp connectors to ensure a durable and reliable connection.
**Replace the Input/Turbine Speed Sensor:** If the wiring and connector are confirmed to be in good condition, and the sensor itself consistently shows intermittent signal loss, incorrect readings, or fails electrical tests, replacing the input/turbine speed sensor is the most direct solution. Always use an OEM-quality replacement part to ensure compatibility and longevity.
**Address Transmission Fluid Issues (If Applicable):** If the transmission fluid was found to be extremely low or severely degraded during diagnosis, correcting the fluid level and/or performing a transmission fluid and filter service might be necessary. While not a direct fix for the electrical circuit, ensuring optimal transmission fluid condition supports proper transmission operation and can prevent future issues that might indirectly affect sensor performance or cause other transmission problems.