OBD-II code · Network
U0679 Lost Communication With Transmission Fluid Pressure Sensor/Switch A
The vehicle bus reports loss of communication with smart transmission fluid pressure sensor / switch A. Hydraulic pressure feedback for shift control is unavailable; TCM may switch to default shift logic.
Is it safe to drive with U0679?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelyBus wiring open or shorted
- PossibleModule without power or ground
- PossibleModule 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
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 0.5–3 h
- Emissions test
- Usually unaffected
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Transmission Fluid Pressure Sensor A, Vehicle Bus Wiring
Related codes
- U067ALost Communication With Transmission Fluid Pressure Sensor/Switch B
- U0676Lost Communication With Fuel Level Sensor A
- U0677Lost Communication With Fuel Level Sensor B
- U0678Lost Communication With Fuel Level Sensor C
- U067BLost Communication With Engine Disconnect Clutch Pressure Sensor
- U067CLost Communication With Fan 3
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.