Transmission Fluid Temperature Sensor 1
Indicates a problem with the transmission fluid temperature sensor.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
The transmission fluid temperature sensor measures how hot the fluid in your transmission is. If it gets too hot, it can cause shifting problems or damage the transmission over time.
What the computer is actually seeing
The computer scans the transmission fluid temperature sensor and expects a voltage signal representing the fluid temperature, typically between 0.5V (about 32°F) and 4.5V (about 300°F). A reading outside of this range triggers the fault code.
What a healthy reading looks like
Voltage signal should be between 0.5V and 4.5V corresponding to temperatures of approximately 32°F to 300°F; normal operation typically around 175°F to 225°F when the engine is warm.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Check the transmission fluid level. Ensure it's between the minimum and maximum marks on the dipstick. If low, fill it to the correct level and check for leaks.
- 22. Inspect the wiring and connectors to the transmission fluid temperature sensor for wear, fraying, or corrosion.
- 33. Using a multimeter, check the voltage output from the transmission fluid temperature sensor at idle. It should be around 0.5V (cold) to 4.5V (hot). If not, the sensor may be faulty.
- 44. If the sensor voltage is correct, connect a scan tool and monitor live data for temperature readings. If the readings are erratic or outside expected values, replace the transmission fluid temperature sensor.
- 55. If all checks are correct, consider testing the transmission control module for faults.
Common causes
- Wiring damage or short
- Faulty transmission fluid temperature sensor
- Low transmission fluid level
- Corroded connectors
- Faulty transmission control module
Typical repair cost
$$-$$$
Related codes
Frequently asked questions
Is it safe to drive with this code active?
It's best to address this code soon; driving with an overheating transmission can cause severe damage.
Will this code come back after clearing it?
If the underlying issue isn't fixed, the code is likely to return.
Does this code mean I need a new transmission?
Not necessarily; many times, it can be resolved by replacing the sensor or fixing wiring issues.
Working a real vehicle right now?
Let DiagCoach walk you through it live with your specific symptoms, vehicle, and what you've already checked.
Start guided diagnostic →