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DTC codes / U06xx · Network communication / U068B

U068BLost Communication With Turbocharger/Supercharger Inlet Pressure Sensor A

U068B is a network communication fault indicating that one or more control modules have lost the CAN (Controller Area Network) signal from the turbocharger or supercharger inlet pressure sensor A. The computer has detected that expected messages from this sensor are missing or intermittent on the data bus, not necessarily that the sensor itself has failed electrically.

SystemNetwork
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaNetwork communication

Symptoms you may notice

  • Illumination of the check engine light or service vehicle soon message with no other noticeable drivability issues
  • Reduced engine power or limp mode triggered by the powertrain control module when boost pressure data is unavailable
  • Rough running, hesitation, or poor acceleration because the engine cannot accurately calculate air charge
  • Intermittent stalling or unstable idle if the missing signal affects fuel delivery calculations
  • Other unrelated warning lights or module communication errors appearing simultaneously due to a shared bus fault

Common causes, most likely first

  1. Damaged, corroded, or disconnected wiring harness at the turbocharger inlet pressure sensor connector
  2. Faulty inlet pressure sensor A that cannot transmit data on the CAN bus
  3. Open or shorted CAN bus wiring between the sensor and the module that publishes its data
  4. Poor ground connection at the sensor or the module responsible for relaying its signal
  5. Failed or intermittently failing control module that hosts the sensor communication
  6. Water intrusion or heat damage in the sensor connector causing intermittent communication
  7. Aftermarket electrical accessories or poor previous repairs introducing bus interference

How to diagnose and fix it

  1. Inspect the inlet pressure sensor connector and harness for corrosion, loose pins, or chafed wires, and repair as needed
  2. Check for technical service bulletins or software updates for the module that communicates with the sensor
  3. Measure CAN bus resistance and voltage at the sensor connector to confirm bus integrity before replacing parts
  4. Perform a wiggle test on the harness while watching live sensor data to expose intermittent communication faults
  5. Verify sensor operation with a scan tool that can read inlet pressure data and compare it to expected values under key-on and running conditions
  6. Replace the turbocharger or supercharger inlet pressure sensor A if communication is lost at the sensor with a known-good bus signal present
  7. Clear the code and perform a road test to confirm the repair, rechecking for any stored or pending communication codes

When the sensor is not the real culprit

  • A U068B code often appears after battery replacement or jump-starting because voltage spikes can momentarily disrupt CAN communication, and the code may not return after clearing.
  • Technicians frequently replace the inlet pressure sensor only to find the real fault is a corroded ground splice shared with other sensors on the same circuit.
  • This code can be set by a failing voltage regulator or weak battery that causes bus voltage to drop below the threshold required for reliable communication.
  • Some vehicles route inlet pressure sensor data through a gateway module, so a fault in the gateway can set U068B even when the sensor and its wiring are perfect.
  • A loose aftermarket air intake or intercooler pipe can vibrate the sensor connector enough to cause intermittent communication loss that only appears under certain driving conditions.

Can I keep driving with U068B?

You can usually drive the vehicle to a repair shop, but avoid heavy acceleration and towing because the engine may enter limp mode without valid boost pressure data. If the engine runs poorly or stalls, stop driving and have the vehicle towed to prevent unsafe conditions.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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