U068B: Lost Communication With Turbocharger/Supercharger Inlet Pressure Sensor A

What it means

The vehicle bus reports loss of communication with smart turbocharger inlet pressure sensor A (compressor inlet). Pressure-ratio computation 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

Turbocharger/supercharger inlet pressure sensor A measures pressure at the compressor inlet and sends its data over the vehicle bus. This code sets when the bus loses the sensor A messages, so the pressure-ratio calculation must use 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 establish when inlet pressure sensor A disappeared and whether the bus has other dropouts.
2. Inspect sensor A's connector and harness at the compressor inlet for loose pins, corrosion, oil or moisture intrusion, heat damage, or chafing.
3. Check the sensor module's power and ground using the manufacturer's procedure, since either fault can make the sensor stop communicating.
4. Inspect the communication wires and splices to sensor A for opens or shorts, then test for continuity and unintended shorts as specified by the manufacturer.
5. If supply and bus wiring are sound, use a capable scan tool to confirm sensor A is unresponsive before replacing the sensor/module.

Common fixes

• Secure or repair the compressor-inlet sensor A connector and damaged terminals.
• Repair an open, short, or damaged splice in the sensor A bus wiring.
• Restore the sensor module's power or ground.
• Replace turbocharger/supercharger inlet pressure sensor A if it remains offline after the circuit checks pass.

Can I keep driving?

A brief, gentle drive may be possible if the engine runs normally, but avoid hard acceleration, towing, and sustained boost because pressure-ratio control is using substitute data. Stop if power becomes erratic or a boost or engine warning appears, and address the fault promptly.