Transmission Fluid Temperature Sensor Circuit
Transmission fluid temperature sensor is out of the expected range.
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What it means (plain English)
The transmission fluid temperature sensor measures how hot the fluid is inside the transmission. If it's too low or too high, it means the sensor is either faulty or the fluid is at an abnormal temperature that could indicate larger transmission problems.
What the computer is actually seeing
The engine control module (ECM) monitors the transmission fluid temperature sensor to keep the transmission in optimal operating conditions. If it detects that the fluid temperature is outside of the normal operating range, it triggers this fault code.
What a healthy reading looks like
Expected voltage from the sensor: 0.5V to 4.5V, corresponding to fluid temperatures from -40°C to 125°C (-40°F to 257°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; it should be within the manufacturer's specifications. If low, add fluid and retest.
- 22. Inspect wiring and connectors for damage, corrosion, or loose connections at the transmission fluid temperature sensor. Repair as necessary.
- 33. Measure voltage at the transmission fluid temperature sensor connector. If voltage is outside expected range (0.5V to 4.5V), suspect a faulty sensor.
- 44. If the sensor is functioning correctly, check for contamination in the transmission fluid; consider flushing if necessary.
- 55. Clear the code and perform a road test to see if the code returns. If yes, consider replacing the sensor.
Common causes
- Faulty transmission fluid temperature sensor
- Poor electrical connection or damaged wiring
- Low transmission fluid level
- Contaminated transmission fluid
- Faulty ECM or software issue
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's moderate severity; it can be driven but fix it soon to avoid potential transmission damage.
Will the code come back?
If the root cause isn't fixed, yes, it will likely come back after clearing.
Why does this code sometimes pair with SPN 600?
SPN 600 indicates transmission oil temperature, often linked with SPN 617 when there's an issue with the related sensor.
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