Transmission Oil Temperature Sensor 1
Indicates an abnormal transmission oil temperature reading.
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What it means (plain English)
The computer is monitoring the transmission fluid temperature, and it thinks the reading is out of range, which could mean the sensor is bad or the fluid is overheating.
What the computer is actually seeing
The Engine Control Module (ECM) reads the temperature of the transmission fluid via the sensor. Normally, this should register between 175°F to 220°F under standard operating conditions. If it reads above 245°F or below 30°F, it triggers this code.
What a healthy reading looks like
The expected temperature range for the transmission fluid should be between 175°F and 220°F. If the recorded temperature is outside this range, the code is set.
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 is within the specified range.
- 22. Inspect wiring and connectors related to the transmission oil temperature sensor. Look for frayed, corroded, or loose connections.
- 33. Using a scan tool, monitor the live data for transmission fluid temperature. Is it reading consistently above 245°F or below 30°F? Yes: go to step 4, No: continue monitoring vehicle.
- 44. If the reading is out of range, replace the transmission oil temperature sensor and clear the code. Test drive the vehicle to see if the code returns.
- 55. If the code returns, check for overheating in the transmission, and diagnose other potential issues like fluid contamination or internal failure.
Common causes
- Faulty transmission oil temperature sensor
- Wiring issues or connector problems
- Low transmission fluid level
- Faulty transmission control module (TCM)
- Overheating transmission due to other issues
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's better to address this issue soon, as overheating the transmission can cause significant damage.
Will this code come back after clearing it?
If the underlying issue isn't fixed, yes, it will return.
Why does this code pair with others like SPN 1544?
They often relate to temperature or pressure readings in the transmission system, indicating multiple issues.
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