What it means
The second transmission fluid temperature sensor signal jumps or drops out intermittently. Loose connector or chafed wire.
At a glance
- Usually lights the check-engine light
How it works
Transmission fluid temperature sensor B reports fluid temperature through a circuit monitored by the transmission control module. This code sets when that signal jumps or drops out intermittently, often because the connector is loose or the harness is chafed or losing contact under vibration.
Common causes
Most likely first.
- Sensor connector not fully seated
- Harness chafed against transmission housing
- Connector with intermittent contact under vibration
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
- Review freeze-frame data and any recorded fault conditions to identify whether the dropout occurred during vibration, movement, or a temperature change.
- Monitor sensor B’s live temperature and gently wiggle its connector and harness to see whether the reading jumps or disappears.
- Inspect the connector for incomplete seating, damaged locks, corroded terminals, or failed seals.
- Follow the sensor B harness along the transmission housing and look for chafing, pinching, or damage where it moves or contacts the housing.
- If no fault is visible, check circuit continuity while flexing the harness and test sensor B using the manufacturer’s procedure.
Common fixes
- Fully seat and secure the sensor B connector.
- Repair chafed or pinched wiring along the transmission housing.
- Replace damaged connector terminals or seals that allow intermittent contact.
- Replace sensor B if its signal drops out while the wiring and connector remain stable.
Can I keep driving?
If the transmission is shifting normally, drive gently and keep trips short until the intermittent connection is repaired. Stop if shifts become erratic or the transmission loses drive; a sudden sensor B dropout can disrupt shift control or trigger 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.