Transmission Fluid Temperature Sensor 1
Indicates an issue with transmission fluid temperature sensor 1.
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What it means (plain English)
The computer is reading an incorrect temperature from the transmission fluid sensor, which should be around 160-220°F during normal operation.
What the computer is actually seeing
The Transmission Control Module (TCM) expects a voltage signal that corresponds to the transmission fluid temperature; typically, 0.5V to 4.5V, where 0.5V indicates around 32°F and 4.5V indicates about 250°F.
What a healthy reading looks like
Expected voltage range is between 0.5V and 4.5V corresponding to fluid temperatures from 32°F to 250°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 wiring and connectors to the transmission fluid temperature sensor for damage or corrosion. If damaged, repair or replace as needed. Decision point: Is wiring intact?
- 22. Measure the voltage at the transmission fluid temperature sensor with the ignition on (engine off). Should be between 0.5V and 4.5V. Decision point: Is voltage within range?
- 33. If the voltage is outside the expected range, replace the sensor. If the voltage is normal but the code persists, inspect the TCM for faults.
Common causes
- Faulty transmission fluid temperature sensor
- Wiring issues or corrosion in the sensor circuit
- Oil contamination affecting sensor operation
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's generally drivable but you may experience erratic transmission behavior; fix it soon.
Will the code return after I reset it?
If the underlying problem is not resolved, yes, the code is likely to come back.
Does this code mean I need a new transmission?
Not necessarily; it usually points to sensor or wiring issues, but further diagnostics are needed.
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