What it means
The fourth transmission fluid temperature sensor reports an over-temperature condition.
At a glance
- Usually lights the check-engine light
How it works
Transmission fluid temperature sensor D reports fluid temperature from the transmission's fourth sensing point. The control module sets this code when that sensor detects a temperature above the system's over-temperature limit; the condition may reflect genuinely hot fluid rather than an electrical signal fault.
Common causes
Most likely first.
- Restricted transmission fluid cooler
- Sustained heavy load such as trailer towing
- Low transmission fluid level
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
- Check freeze-frame data and live temperature readings to confirm sensor D reported overheating and note the driving conditions when it occurred.
- If the transmission is hot or showing a warning, stop safely and let it cool before checking fluid or inspecting components.
- Inspect for signs of low fluid or leakage and check the fluid level using the vehicle manufacturer's procedure.
- Inspect the transmission cooler and its lines for damage, blockage, kinks, or restricted airflow.
- If the fluid level and cooler appear normal but sensor D still reports overheating, check its reading and circuit against the manufacturer's specification.
Common fixes
- Correct low transmission fluid using the manufacturer's specified fluid and checking procedure, and repair any leak.
- Remove an external obstruction restricting airflow through the transmission cooler.
- Repair damaged or kinked cooler lines or a restricted cooler as indicated by inspection.
- Replace sensor D if it falsely reports over-temperature and its circuit checks out.
Can I keep driving?
If the transmission is overheating, stop in a safe place and let it cool; do not tow or continue strenuous driving. Driving with genuinely overheated fluid can worsen slipping and damage the transmission.
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.