Engine Automatic Transmission Fluid Temperature
Indicates the fluid temperature in the automatic transmission is out of range.
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What it means (plain English)
The transmission has a sensor that measures fluid temperature. If the temperature goes above or below a certain point (about 32°F to 248°F), the computer gets a warning.
What the computer is actually seeing
The engine control module (ECM) receives input from the transmission fluid temperature sensor. Values outside of the normal range trigger a fault code.
What a healthy reading looks like
Normal transmission fluid temperature for optimal performance is typically between 150°F and 200°F (66°C - 93°C).
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 fluid level of the transmission. Ensure it's in the correct range. If low, top off with the recommended fluid.
- 22. Inspect the transmission fluid temperature sensor wiring and connector for damage, corrosion, or loose connections.
- 33. Measure the resistance of the transmission fluid temperature sensor at room temperature (should be around 2000 to 3000 ohms) and compare to manufacturer specs.
- 44. If wiring and sensor check out, connect a scan tool to monitor the temperature reading live while the engine runs. Ensure it reflects expected changes as the engine warms up.
Common causes
- Faulty transmission fluid temperature sensor
- Wiring issues or shorts in the sensor circuit
- Low transmission fluid
- Ground issues affecting the sensor signal
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's drivable, but transmission performance might be affected; consider fixing it soon.
Will this code come back after clearing?
It can return if the underlying issue isn't resolved.
Why does this code pair with other SPNs?
Codes SPN 520 and 523 are related to temperature and sensor issues; they may indicate the same problem.
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