What it means
The vehicle bus reports loss of communication with smart transmission fluid pressure sensor / switch B. Hydraulic pressure feedback for shift control is unavailable; TCM may switch to default shift logic.
At a glance
- Usually lights the warning light of the system that lost communication
- The engine or gearbox may go into limp mode
How it works
Smart transmission fluid pressure sensor or switch B sends hydraulic pressure feedback over the vehicle network to support shift control. U067A sets when the receiving module loses messages from sensor B, and the transmission control module may switch to default shift logic without that feedback.
Common causes
Most likely first.
- Bus wiring open or shorted
- Module without power or ground
- Module failed
Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
How to diagnose it
- Scan all modules for communication and transmission codes, preserving freeze-frame data to see whether sensor B's loss coincides with other network faults.
- Check live data for pressure sensor or switch B and record any missing reading, harsh shifts, or limp-mode behavior.
- Inspect sensor B's connector and wiring for loose pins, corrosion, fluid intrusion, or harness damage.
- Check the power and ground supplied to sensor B or its module against the manufacturer's specification.
- Test the network wiring serving sensor B for opens or shorts according to the manufacturer's procedure.
- If the bus and supply circuits pass, use the manufacturer's procedure to confirm failure of sensor B or its communication module.
Common fixes
- Reconnect or clean sensor B's connector and repair damaged wiring.
- Restore a faulty power or ground connection to sensor B or its module.
- Repair an open or short in the network wiring to pressure sensor or switch B.
- Replace the confirmed failed sensor B or communication module.
Can I keep driving?
Drive gently only if shifts remain predictable; avoid towing and hard acceleration while the transmission lacks pressure feedback. If it slips, shifts violently, will not engage, or overheats, stop driving because further operation can 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.