Transmission Fluid Temperature Sensor Circuit Low Input
The transmission fluid temperature sensor is reading too low a voltage.
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What it means (plain English)
The computer expects to see a certain voltage from the transmission fluid temperature sensor but is getting a lower voltage, indicating a possible sensor issue or wiring problem.
What the computer is actually seeing
The transmission control module (TCM) sees lower than expected voltage from the fluid temperature sensor, typically below 0.2 volts when it should be in the range of 0.5 to 4.5 volts depending on the temperature.
What a healthy reading looks like
Voltage from the sensor should be between 0.5 to 4.5 volts, depending on fluid temperature; typically around 1.5 volts at 40°C (104°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 transmission fluid level and condition; ensure it's full and not burnt.
- 22. Inspect wiring and connectors related to the transmission fluid temperature sensor for damage or corrosion.
- 33. Measure voltage at the sensor connector with the key on (engine off); expect 0.5 to 4.5 volts. If below 0.2 volts, go to step 4.
- 44. Disconnect the sensor and measure continuity in the wiring back to the TCM connector. Replace damaged wiring if found.
- 55. If wiring is good, replace the transmission fluid temperature sensor and retest.
- 66. Clear the code and take the vehicle for a drive cycle. If the code returns immediately, suspect the TCM.
Common causes
- Faulty transmission fluid temperature sensor
- Wiring issues (open or short circuits)
- Connector issues (corrosion or damage)
- Faulty transmission control module (rare)
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's drivable but the transmission may shift erratically; fix soon.
Will this code come back after clearing?
It might return if the underlying issue isn't resolved.
Why does this code pair with P0811?
P0811 also relates to transmission temperature but indicates a high input problem, potentially connected to similar faults.
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