Damaged, chafed or corroded wiring to the input speed sensor; Loose, corroded or contaminated connector at the sensor or transmission control module; Failing input/turbine speed sensor giving a dropout or noisy signal; Metal debris or contamination on the sensor tip or reluctor ring; Transmission fluid leaking or seeping into the sensor connector or harness; Low or degraded transmission fluid affecting the sensor signal or gearbox operation; Faulty transmission control module or internal gearbox damage affecting the input shaft or reluctor.

P0718

Input/Turbine Shaft Speed Sensor A Circuit Intermittent.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
7: AreaTransmission
18: FaultThe specific fault in that area

What it means

P0718 means the transmission control module has detected an intermittent fault in the input/turbine shaft speed sensor 'A' circuit. The signal drops out, becomes erratic or is briefly lost while driving, so it does not match expected behaviour compared with engine speed, output speed or the selected gear. Because it is intermittent, the fault may come and go and the warning light may clear itself if it does not return.

Symptoms

Gearbox warning light or malfunction indicator lamp on
Erratic or flickering speedometer or rev reading on some vehicles
Harsh, delayed or flared gear shifts
Gearbox stuck in one gear (limp mode)
Torque converter lock-up not working, with higher fuel consumption
Problem appears and disappears, often with vibration, heat or damp

Possible causes

Damaged, chafed or corroded wiring to the input speed sensorlikely
Loose, corroded or contaminated connector at the sensor or transmission control modulelikely
Failing input/turbine speed sensor giving a dropout or noisy signallikely
Metal debris or contamination on the sensor tip or reluctor ringpossible
Transmission fluid leaking or seeping into the sensor connector or harnesspossible
Low or degraded transmission fluid affecting the sensor signal or gearbox operationpossible
Faulty transmission control module or internal gearbox damage affecting the input shaft or reluctorrare

How to diagnose

Read all stored codes and freeze frame data, noting speed, gear and temperature when the fault set, and check for other speed sensor or communication codes
Check for relevant manufacturer service information or software updates for your model, as the sensor location and type vary by gearbox
Inspect the wiring and connector to the input speed sensor for chafing, heat damage, corrosion, fluid ingress and poor pin tension
Check the transmission fluid level and condition, following the manufacturer procedure for that gearbox, and look for leaks
Monitor live input shaft speed, output speed and engine speed on a road test and look for dropouts or spikes, while wiggling the harness
Test sensor circuit resistance, supply and signal against specification for your model
Remove the sensor and inspect the tip and reluctor ring for debris, damage or excessive wear where accessible
Clear the codes and retest to confirm the fault does not return

How to fix

Repair or replace damaged wiring and fix any chafing points
Clean or replace corroded or loose connectors and terminals
Replace the input/turbine speed sensor if the signal is faulty or erratic
Clean off debris and rectify the cause of contamination, repairing internal damage if found
Fix any fluid leak and correct the fluid level or change the fluid as the manufacturer specifies
Update the software or replace the transmission control module only if testing proves it faulty or an update is specified

Can I keep driving?

Medium severity

The car can usually be driven short distances, but the gearbox may shift harshly or enter limp mode without warning. Have it checked soon, as continued driving with poor shifting can cause extra wear or leave you with limited gears.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.