U0680: Lost Communication With Barometric Pressure Sensor B

What it means

The vehicle bus reports loss of communication with smart barometric pressure sensor B. Altitude correction for engine fueling and EVAP diagnostics switches to a substitute value.

At a glance

• Usually lights the warning light of the system that lost communication
• Affects emissions; the car can fail an emissions test

How it works

Barometric pressure sensor B is a networked sensor that reports atmospheric pressure for altitude-related engine fueling and evaporative-emissions checks. This code sets when the vehicle network stops receiving messages from sensor B, so those calculations may fall back to a substitute value.

Common causes

Most likely first.

1. Bus wiring open or shorted
2. Module without power or ground
3. 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

1. Save freeze-frame data and scan all modules for communication codes to determine whether sensor B alone or other network devices also dropped offline.
2. Check live data for sensor B's pressure reading and communication status, comparing it with other available pressure readings.
3. Inspect sensor B's connector and bus wiring for loose or bent pins, corrosion, moisture, abrasion, or breaks.
4. Verify sensor B's power and ground according to the manufacturer's procedure to rule out a supply fault.
5. Test the bus branch for opens or shorts using the manufacturer's procedure, then evaluate sensor B or its module if the wiring and supplies pass.

Common fixes

• Secure or clean sensor B's loose or corroded connector.
• Repair an open, short, or damaged terminal in sensor B's bus wiring.
• Repair the sensor or module power and ground connections.
• Replace sensor B or its module if tests confirm an internal communication failure.

Can I keep driving?

A brief, gentle drive may be possible if the vehicle behaves normally, but some altitude corrections and EVAP diagnostics may be impaired. Avoid continuing if drivability changes or additional warning lights appear.