Transmission Fluid Temperature High
The transmission fluid temperature is too high according to the engine control unit.
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What it means (plain English)
The computer is reading that the transmission fluid is too hot, which can cause transmission damage if not resolved. It should be around 160°F to 200°F under normal operation.
What the computer is actually seeing
The engine control unit (ECU) monitors the transmission fluid temperature sensor input and flags a fault when it detects temperatures above 250°F or if the signal is out of range.
What a healthy reading looks like
Normal transmission fluid temperature should be between 160°F and 200°F. Above 250°F will trigger the 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 transmission fluid level. It should be at the right mark on the dipstick. If low, fill it to the proper level. Decision: If fluid was low, check for leaks or further issues causing the drop.
- 22. Inspect the wiring and connectors at the transmission fluid temperature sensor for damage or corrosion. Ensure the connector is securely attached. Decision: If damaged, repair or replace the wiring/connectors.
- 33. Test the transmission fluid temperature sensor with a multimeter. Verify resistance/voltage output at various temperatures. Expected voltage should change with temperature, aiming for a range of 0.5V (cold) to 4.5V (hot). Decision: If the sensor is out of this range, replace it.
- 44. If the sensor and wiring are good, check for conditions that might cause overheating: towing, high ambient temperatures, or other mechanical failures in the cooling system. Decision: Address any mechanical issues or reduce load and see if the code returns.
Common causes
- Low transmission fluid level
- Faulty or damaged transmission fluid temperature sensor
- Bad electrical connection or wiring to the temperature sensor
- Overheating due to towing heavy loads or hot conditions
- Cooling system issues affecting transmission cooler operation
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's best not to drive excessively until the issue is resolved. High transmission temperatures can cause significant damage.
Will this code come back after clearing?
If the underlying issue is not fixed—like a sensor or cooling problem—the code will likely return.
Why does this code pair with SPN 732 or SPN 731?
These codes are often related, as they indicate temperature issues within the transmission system and provide a broader view of transmission health.
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