What it means
The fourth transmission fluid temperature sensor signal is above the upper diagnostic threshold. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
At a glance
- Usually lights the check-engine light
How it works
Transmission fluid temperature sensor D measures fluid temperature at the fourth sensing point in the transmission. The control module monitors its circuit signal; this code sets when the signal rises above the upper diagnostic threshold, which can result from an open sensor element or a signal circuit shorted to voltage.
Common causes
Most likely first.
- Open sensor element
- Signal wire shorted to the 5 V reference
- 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
- Use freeze-frame and live data to confirm sensor D is reporting an unusually high or fixed reading and record when the fault occurs.
- Inspect sensor D's connector and harness for an unplugged connector, broken wire, corrosion, moisture, or damaged pins.
- Wiggle the sensor D harness while monitoring the reading to check whether a loose or damaged connection makes the signal change.
- Check the signal wire for an open circuit or a short to the reference or other voltage source, following the vehicle's wiring information.
- Test sensor D and the circuit against the manufacturer's specification to determine whether the sensor element is open or the wiring is at fault.
Common fixes
- Reconnect and secure sensor D's connector.
- Repair an open or voltage-shorted wire in the sensor D circuit.
- Repair corroded, damaged, or poorly seated connector terminals.
- Replace sensor D if the circuit is sound and its element remains open or out of specification.
Can I keep driving?
Avoid towing or hard driving if shifts are abnormal, and stop if the transmission slips or cannot shift safely. An implausibly high temperature signal can disrupt shift control or trigger protective operation even when the fluid is not actually overheated.
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.