Transmission Fluid Temperature Sensor 1 - Voltage Out of Range
The transmission fluid temperature sensor is reporting a voltage that’s too high or too low.
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What it means (plain English)
Inside the transmission, there's a sensor measuring the fluid's temperature. This sensor sends its voltage signal to the computer. If the transmission fluid gets too hot or cold, it affects the voltage—outside the expected range—causing issues with shifting and performance.
What the computer is actually seeing
The computer expects voltage between 0.5V and 4.5V, corresponding to a fluid temperature of -40°C to 150°C (-40°F to 302°F). Any voltage outside this range indicates a problem.
What a healthy reading looks like
0.5V to 4.5V corresponding to -40°C to 150°C (-40°F to 302°F).
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; add fluid if low.
- 22. Inspect wiring and connectors to the temperature sensor for damage or corrosion.
- 33. Measure the voltage at the temperature sensor connector with a multimeter; verify it’s within 0.5V to 4.5V when the engine is running.
- 44. If the voltage is out of range, swap the temperature sensor with a known good one. If the problem resolves, replace the sensor.
Common causes
- Faulty transmission fluid temperature sensor
- Corroded or damaged wiring or connectors
- Low transmission fluid level
- Contaminated transmission fluid
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this fault code?
It's not recommended to drive, as it can lead to transmission overheating or other issues.
Will this code come back after clearing it?
If the condition causing the code isn’t fixed, it will likely return.
Why does this code appear with other SPN codes?
Multiple sensors can fail or experience issues simultaneously, especially in high-temperature environments.
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