U0679 — Lost Communication With Transmission Fluid Pressure Sensor/Switch A

What Does U0679 Mean?

U0679 is a diagnostic trouble code indicating: Lost Communication With Transmission Fluid Pressure Sensor/Switch A. This code relates to the vehicle systems system. The vehicle's computer detected a condition outside normal operating parameters and stored this code.

Symptoms of U0679

⚠️ Check Engine Light (MIL) illuminated
⚠️ No communication with Transmission Fluid Pressure Sensor/Switch A
⚠️ Multiple warning lights may illuminate simultaneously
⚠️ Related system completely inoperative
⚠️ System warning light illuminated

Common Causes

🔍 CAN bus wiring fault (open or shorted) to Transmission Fluid Pressure Sensor/Switch A
🔍 Power or ground supply issue to Transmission Fluid Pressure Sensor/Switch A
🔍 Transmission Fluid Pressure Sensor/Switch A internal failure
🔍 Water intrusion damaging module or connectors
🔍 CAN bus termination resistor fault

Frequently Asked Questions

What does U0679 mean?

U0679 indicates: Lost Communication With Transmission Fluid Pressure Sensor/Switch A. The vehicle's computer has detected that the Transmission Fluid Pressure Sensor/Switch A is not operating within its expected parameters and stored this diagnostic trouble code.

Can I drive with code U0679?

You can drive short distances for essential trips, but schedule a diagnosis soon. Driving with U0679 for extended periods may cause additional problems.

How much does it cost to fix U0679?

Repair costs for U0679 typically range from $80 to $800, depending on the root cause. Simple wiring or connector repairs are on the lower end, while component replacement costs more. A proper diagnosis ($80–$150 at most shops) will identify the exact cause before committing to expensive parts.

What To Do Next

Possible Fixes

🔧 Inspect CAN bus wiring to Transmission Fluid Pressure Sensor/Switch A for damage
🔧 Check power and ground supply to Transmission Fluid Pressure Sensor/Switch A
🔧 Replace failed Transmission Fluid Pressure Sensor/Switch A

1
Find your vehicle above
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2
Check for recalls
Go to nhtsa.gov/recalls and enter your VIN. Free repairs if covered.
3
Get a professional diagnosis
A code alone doesn't identify the exact failed part. A diagnostic ($50–$150) pinpoints the root cause.

U0679: Lost Communication With Transmission Fluid Pressure Sensor/Switch A