U068A: Lost Communication With Barometric Pressure Sensor C

What it means

The vehicle bus reports loss of communication with smart barometric pressure sensor C. 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 C is a smart sensor that reports atmospheric pressure over the vehicle communication bus. This code sets when its messages are lost, so the engine and emissions controls use a substitute pressure value for altitude-related fueling corrections and EVAP diagnostics.

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 identify when sensor C went offline and whether other bus devices also lost contact.
2. Inspect the barometric pressure sensor C connector and harness for loose pins, corrosion, moisture, or chafing.
3. Check the sensor module's power and ground according to the manufacturer's procedure, because a missing supply or ground can stop bus communication.
4. Inspect the communication wiring and splices serving sensor C for opens or shorts, then test the circuit as specified by the manufacturer.
5. If the wiring and supply circuits check out, confirm with a capable scan tool whether sensor C responds on the bus before replacing its module.

Common fixes

• Reconnect or clean a loose or corroded sensor C connector and repair damaged terminals.
• Repair an open, short, or damaged splice in the sensor's communication wiring.
• Restore the sensor module's power or ground.
• Replace barometric pressure sensor C if it remains unreachable with sound wiring, power, and ground.

Can I keep driving?

If the vehicle runs normally, a short trip is generally reasonable, but arrange diagnosis soon because substitute altitude data can affect fueling and EVAP monitoring. Avoid relying on the vehicle for emissions readiness until communication is restored.