Input/Turbine Speed Sensor A Circuit Intermittent
The P0718 code indicates an intermittent signal from the input/turbine speed sensor (also known as the transmission speed sensor) in the transmission. This sensor monitors the rotational speed of the torque converter turbine, which is critical for proper transmission shift timing and torque converter lockup. An intermittent circuit means the signal is dropping out or fluctuating, often due to wiring issues, connector corrosion, or a failing sensor. This can cause erratic shifting, harsh engagement, or limp mode.
01. Most Common Causes
- Faulty input/turbine speed sensor
- Damaged or corroded wiring/connectors
- Intermittent short or open in the sensor circuit
- Low transmission fluid level or contamination
- Internal transmission mechanical failure (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Erratic or harsh shifting
- Transmission slipping or delayed engagement
- Torque converter clutch (TCC) not locking properly
- Vehicle may enter limp mode
03. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data to confirm P0718 and check for related codes.
Step 2: Inspect the sensor and wiring for damage, corrosion, or loose connections; repair as needed.
Step 3: Test sensor resistance and AC voltage output while rotating the transmission; compare to specs.
Step 4: Check transmission fluid level and condition; top off or replace if necessary.
Step 5: If all else fails, replace the input/turbine speed sensor and clear codes.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as the transmission may shift erratically or fail to lock the torque converter, potentially causing overheating or internal damage. Limp mode may limit speed and drivability.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for a DIY sensor replacement, or $150 to $400 at a shop including labor and diagnostics.