This sensor measures how fast the transmission's input shaft is spinning, which the TCM uses (together with the output/vehicle speed sensor) to calculate what gear the transmission should be in. A faulty signal here confuses the shift logic even if the transmission's mechanical parts are fine.
Symptoms
- Harsh, delayed, or erratic shifting
- Transmission may enter limp mode, restricting it to one gear
- Shift flare — RPM briefly spikes during a shift before the next gear engages
- Transmission warning light on
Likely causes
- Failed input/turbine speed sensor
- Damaged or corroded wiring/connector, often from transmission fluid contamination at the connector
- Debris or metal shavings on the sensor tip from internal transmission wear
How to diagnose it
- Check the sensor's wiring and connector for fluid contamination or damage
- Compare the sensor's live signal against the output speed sensor with a scan tool while driving
- If accessible, inspect the sensor tip for metal debris, which can also hint at broader internal wear
Typical fixes & cost
- Replace the input/turbine speed sensor100–350 EUR
- Repair wiring or connector80–250 EUR
Code names are compiled from open/standardized SAE and ISO references. Explanations, symptoms, causes and fixes are original. Covers generic (P0/C0/B0/U0) codes only — manufacturer-specific codes are planned for a future update.
AS
Reviewed by Artyom SemenovAutomotive Editor · Fact-checked by Yauheni Kapliarchuk, Editor-in-Chief