What it means
The second 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 B sends its temperature signal to the transmission control module. This code sets when the signal rises above the circuit’s upper diagnostic threshold, often because the sensor element or signal path is open or the signal wire is shorted to its reference 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
- Check freeze-frame data and live sensor B temperature to see whether the signal is abnormally high, fixed, or intermittent.
- With the transmission cold, compare sensor B’s reading with ambient temperature and other available temperature readings.
- Inspect the sensor B connector and harness for broken wires, loose terminals, corrosion, chafing, or water intrusion.
- Check the sensor B signal for an open circuit or short to the reference voltage using the manufacturer’s wiring diagram and procedure.
- If the circuit is intact, test sensor B for an open sensor element and replace it only if it fails the specified checks.
Common fixes
- Repair an open or damaged sensor B signal wire.
- Repair a short between the sensor B signal and its reference-voltage wire.
- Clean or replace corroded or loose connector terminals.
- Replace sensor B if its element is open and the wiring tests correctly.
Can I keep driving?
Limit driving to necessary trips and avoid towing until sensor B’s circuit is checked. If shifting becomes harsh, delayed, or unreliable, stop safely; a falsely high temperature reading may cause the transmission to alter shift control or enter limp mode.
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.