Transmission Fluid Temperature Sensor Stuck High
The P1718 code indicates that the transmission control module (TCM) has detected the transmission fluid temperature (TFT) sensor reading is stuck above 250°F (121°C). This is an abnormally high temperature that can cause transmission damage. The sensor may be faulty, shorted, or there could be a wiring issue. Actual transmission overheating due to low fluid, a failing torque converter, or a clogged cooler can also cause this reading.
1. Symptoms You Will Notice
- Check Engine Light illuminated
- Transmission shifting harsh or erratic
- Transmission slipping or overheating
- Reduced fuel economy
- Transmission may enter limp mode
2. Most Common Causes
- Faulty or out-of-calibration TFT sensor
- Abnormal parasitic resistance in TFT sensor connector or wiring
- Correlated failure of engine coolant temperature (ECT) sensor or ambient temperature sensor
- TCM voltage reference or ground circuit issues
- Transmission fluid temperature genuinely abnormally low (e.g., extreme cold operation)
3. Step-by-Step Diagnosis
Step 1: Scan for additional codes and check freeze frame data.
Step 2: Inspect transmission fluid level and condition; top off or replace if necessary.
Step 3: Visually inspect TFT sensor wiring and connector for damage or corrosion.
Step 4: Test TFT sensor resistance with a multimeter and compare to specifications.
Step 5: Check transmission cooler and lines for blockages or leaks.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
No, driving with a TFT sensor stuck high can lead to transmission overheating and severe damage. Have it diagnosed and repaired as soon as possible.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for a sensor replacement, but if the transmission is damaged, repairs can be much higher.
5. Commonly Affected Makes
This is a manufacturer-specific code. The exact manufacturer is not confirmed in our current database.