What it means
ATF temperature sensor signal voltage below the lower threshold — open, short to ground, or sensor fault.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Transmission fluid temperature sensor A sends a temperature-dependent electrical signal to the TCM. P0712 sets when the signal voltage falls below the expected range, which can happen if the circuit is grounded, open, or the sensor has failed; the TCM may then use a fallback value and limit shifting.
Common causes
Most likely first.
- Transmission temperature sensor failed
- Wiring or connector fault
- Connector pins corroded - high contact resistance
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
How to diagnose it
- Record freeze-frame data and check sensor A's live temperature; compare it with ambient temperature when the transmission is cold to spot an implausible fixed reading.
- Inspect sensor A's connector and wiring for corrosion, fluid, loose or pushed-back pins, and damage that could pull the signal low.
- With the manufacturer's wiring information, check the sensor circuit for a short to ground, an open, or excessive resistance.
- Test the sensor and its reference and return circuits according to the manufacturer's procedure to distinguish a failed sensor from a harness fault.
- After repair, clear the code and confirm sensor A reports a plausible temperature and the transmission shifts normally.
Common fixes
- Clean and secure corroded or loose connector terminals.
- Repair a shorted, open, or damaged wire in sensor A's circuit.
- Replace transmission fluid temperature sensor A if it fails the specified test.
- Restore proper fluid level or condition if inspection identifies a separate transmission issue.
Can I keep driving?
Because this fault can trigger limp mode or disrupt shifts, avoid unnecessary driving and do not tow or accelerate hard. Stop if the transmission slips, loses drive, or shifts unpredictably, and arrange prompt repair.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.