Transmission Fluid Temperature Sensor Circuit Low
The transmission fluid temperature sensor is reading lower than expected values.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
The transmission fluid temperature sensor is telling the computer that the fluid temperature is too low, which can cause the transmission to operate poorly.
What the computer is actually seeing
The engine control module (ECM) or transmission control module (TCM) sees a voltage signal from the transmission fluid temperature sensor that is below the manufacturer’s specifications, usually less than 0.5 volts or the equivalent resistance indicating low temperature.
What a healthy reading looks like
A properly functioning transmission fluid temperature sensor should read between 80°F (27°C) and 250°F (121°C) under normal operating conditions.
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. Inspect the transmission fluid level and condition. Ensure it is at the correct level and not burnt or contaminated.
- 22. Check the wiring and connectors for the transmission fluid temperature sensor. Look for damage, corrosion, or loose connections.
- 33. Measure the voltage at the sensor connector with the key on (engine off). You should see a voltage signal typically around 5 volts.
- 44. If you see low voltage (<0.5 volts), check the wiring continuity back to the ECM/TCM.
- 55. If the wiring is fine, replace the transmission fluid temperature sensor and clear the codes. Recheck the operation.
Common causes
- Faulty transmission fluid temperature sensor
- Wiring issues (shorts, opens, or corrosion)
- ECM/TCM software glitch
- Poor transmission fluid condition or low level
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with SPN 741 active?
It's moderate severity; you can drive, but shifts may be rough and overheating is possible.
Will this code come back after clearing it?
If the underlying issue isn't fixed, the code will reappear.
Why does this code sometimes pair with SPN 739?
Both codes relate to transmission temperature issues; SPN 739 deals with high temperature readings.
Working a real vehicle right now?
Let DiagCoach walk you through it live with your specific symptoms, vehicle, and what you've already checked.
Start guided diagnostic →