P0712 Code: Transmission Fluid Temperature Sensor A Circuit Low
The fluid temperature signal voltage is too low, so the computer thinks the fluid is extremely hot.
At a glance
Severity: Moderate
- Meaning
- Transmission Fluid Temperature Sensor A Circuit Low
- System
- Transmission · Powertrain
- Safe to drive?
- With caution
- Typical repair cost
- $80–$800
- DIY difficulty
- Hard
The module feeds the fluid temperature sensor through a resistor, usually from a 5-volt supply, and reads the voltage left over. Because the sensor's resistance drops as the fluid heats up, a low voltage normally means hot fluid. P0712 sets when the voltage falls below anything real fluid could produce – the scan tool then typically shows the maximum value, often around 300 °F. The usual cause is a short to ground: the signal wire pinched between the pan and the case, insulation worn through on the valve body, a sensor shorted internally, or metal debris or moisture bridging the pins. Many transmissions react with a 'hot mode' strategy, and some drop into limp mode.
Can I keep driving? You can usually drive carefully to a shop, but the transmission may shift oddly, lock the converter early or limit power. If you also smell burnt fluid or see a genuine temperature warning after heavy use, let it cool before continuing – a real overheat normally sets its own over-temperature code rather than P0712.
How to read P0712
- P Powertrain
- 0 Generic (SAE)
- 7 Transmission
- 12 Specific fault
Symptoms
- Scan tool shows fluid temperature pegged at maximum, even on a cold start
- Transmission overheat warning right after starting a cold engine
- Converter clutch locks at unusually low speed, causing shudder or bucking
- Altered shift points or limp mode with a fixed gear
- Reduced engine power on some models to protect the transmission
- Check engine light, often with P0700
Possible causes
Ranked by how often each cause is behind this code (editorial estimate).
- Sensor signal wire shorted to ground inside the transmission (pinched by pan or bracket)
- TFT sensor internally shorted
- Metal debris or moisture bridging pins in the case connector
- External harness chafed against the case or exhaust
- Transmission module input fault
- Incorrect pan or filter fitted after a service, crushing the internal harness
Diagnosis step by step
Check the reading on a cold car
Before starting a car that has sat overnight, look at the transmission temperature on the scan tool. If it reads near maximum while the coolant reads ambient, the circuit is being pulled low – no real overheat is involved.
Tools: OBD-II scanner
Unplug the transmission connector
Disconnect the main case connector with the key on. The reading should immediately drop to the coldest value (around -40 °F). If it does, the short is inside the transmission; if it stays hot, the short is in the external harness or the module.
Tools: OBD-II scanner, Screwdriver
Measure resistance to ground at the case
At the transmission side of the connector, measure between the TFT signal pin and the case. There should be no continuity; a low reading confirms an internal short, while a few ohms across the two sensor pins points to a shorted sensor.
Tools: Multimeter
Inspect the connector for debris
Look closely at the connector pins and the pass-through on the case. Fine metallic paste or water between pins can create a leakage path; clean with electrical contact cleaner and dry before retesting.
Tools: Flashlight, Soft brush
Drop the pan and inspect the internal harness
With the fluid drained, trace the internal harness for flattened or cut insulation where it runs near the pan rail, filter and valve body bolts. Repair or replace the harness or sensor, then refill using the correct temperature-based level procedure.
Tools: Towels & shallow pan, Torque wrench, Flashlight
Where the parts are
- 1Battery
- 2Alternator
- 3Engine computer (ECM)
- 4CAN bus
- 5Transmission
- 6Wheel speed sensor
- 7High-voltage battery
Repair options & costs
| Repair | DIY? | Estimated cost |
|---|---|---|
| Clean case connector, remove debris and moisture | Yes | $80–$200 |
| Repair external harness short | No | $120–$350 |
| Replace TFT sensor with pan, gasket and fluid | No | $200–$450 |
| Replace internal harness or lead frame | No | $350–$800 |
Rough US estimates for parts and labor; shop rates vary by region. Not a quote.
Emissions / smog test impact
Will fail
The check engine light stays on with P0712, so the vehicle fails an OBD emissions or smog test until the short is repaired and the code stays clear.
Frequently asked questions
Does P0712 mean my transmission is overheating?
Usually not. It means the signal voltage is lower than even very hot fluid could produce, which points to a short to ground. A cold car showing maximum transmission temperature is the giveaway.
Why does unplugging the connector help find the fault?
An unplugged sensor looks like an extremely cold reading. If the value drops to minimum when you unplug at the transmission, the short is inside; if it stays at maximum, the short sits in the wiring or the module on the other side.
Why does my car shudder at low speed with this code?
Many transmissions lock the torque converter early when they think the fluid is hot, to reduce heat. Locking up at low speed and light load can feel like driving over rumble strips.
Can a fluid change cause P0712?
It can if the pan, filter or a bracket was installed so that it pinches the internal harness, or if metal debris ended up on the connector. When the code appears right after a service, check that area first.