Transmission Temperature Sensor (TTS) Circuit High
Transmission temperature sensor signal is too high or shorted to voltage.
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What it means (plain English)
The transmission temperature sensor is sending a signal indicating the fluid is hotter than a certain threshold, typically over 300°F, which isn’t normal for operation.
What the computer is actually seeing
The Engine Control Module (ECM) receives a voltage reading from the temperature sensor, generally expected to range between 0.5V (at low temps) to 4.5V (at high temps). If it sees values above 4.5V, it sets this code.
What a healthy reading looks like
Transmission fluid temperature should operate between 150°F and 250°F. Any signal over 4.5V or unrealistic temperatures will trigger this code.
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 within the proper range; low fluid can cause overheating. Decision: Is the fluid level okay? Yes = go to step 2; No = fill fluid and retest.
- 22. Inspect the wiring and connectors to the transmission temperature sensor for damage, corrosion, or disconnection. Decision: Are all connections secure and undamaged? Yes = go to step 3; No = repair wiring or connections and retest.
- 33. Use a multimeter to check the resistance of the transmission temperature sensor. At room temperature, you should see around 1.5k ohms; this will vary with temperature. Decision: Is the sensor within the expected resistance range? Yes = go to step 4; No = replace sensor and retest.
- 44. Start the engine and monitor the transmission temperature reading with a scan tool. Decision: Is the temperature reading now within normal limits? Yes = code is resolved; No = replace the transmission temperature sensor and retest.
Common causes
- Shorted wiring harness
- Failed transmission temperature sensor
- Corroded connectors
- Excessive transmission fluid temperatures due to other issues
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
Not recommended. High transmission temperatures can lead to transmission failure.
Will the code come back after repair?
If the root cause is properly fixed, the code should not return.
Why does this code appear along with other codes?
Other codes may relate to transmission operation, indicating a systemic issue with temperature management or fluid flow.
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