What it means
The transmission control module monitors the circuit for transmission fluid temperature sensor B. This code sets when the circuit signal is outside the expected electrical range; the title does not specify the type of circuit fault.
At a glance
- Usually lights the check-engine light
How it works
Transmission fluid temperature sensor B reports fluid temperature to the transmission control module through an electrical circuit. This code sets when the circuit signal is outside its expected electrical range; the code alone does not identify whether the cause is an open, short, or connection fault.
Common causes
Most likely first.
- Open sensor element or broken sensor wire
- Corroded sensor connector
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 its reading is missing, implausible, or changes when the fault occurs.
- With the transmission cold, compare sensor B’s reading with ambient temperature and other available temperature readings.
- Inspect sensor B’s connector and visible harness for corrosion, loose fit, broken wires, or fluid and water intrusion.
- Check the sensor B circuit for continuity, shorts, and terminal condition using the manufacturer’s wiring diagram and test procedure.
- If the wiring checks out, test sensor B itself and replace it only if it fails the specified electrical checks.
Common fixes
- Reconnect and secure a loose sensor B connector.
- Clean or repair corroded terminals and damaged wiring in the sensor B circuit.
- Repair an open or short in the sensor B harness.
- Replace transmission fluid temperature sensor B if testing confirms it has failed.
Can I keep driving?
If the transmission shifts normally, limit driving to necessary trips and avoid towing until sensor B’s circuit is checked. If shifting becomes harsh, delayed, or unreliable, stop safely; incorrect temperature information can cause poor transmission control or 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.