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Home / DTC / U068B — Lost Communication With Turbocharger/Supercharger Inlet Pressure Sensor A

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

Detailed page for trouble code U068B.

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Code

U068B

Generic U — Network/User

Lost Communication With Turbocharger/Supercharger Inlet Pressure Sensor A

Brand: Generic
Type: U — Network/User
Views: UK: 12 EN: 15 RU: 10
AI status
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Page language: EN

Causes

  • Open, shorted or corroded wiring or connector between sensor and control module
  • Faulty turbocharger/supercharger inlet pressure sensor (internal electronics)
  • Loss of sensor power (reference voltage) or ground
  • Faults on vehicle network (CAN/LIN) carrying the sensor message
  • Intermittent connection (water intrusion, damaged pins, loose connector)
  • Faulty engine control module (ECM/PCM) or sensor sub-module software error

Symptoms

  • Check Engine/Malfunction Indicator lamp illuminated
  • Reduced engine power or limp-home mode
  • Poor or erratic turbo boost control (overboost or underboost)
  • Hesitation, reduced acceleration or poor drivability
  • Possible stored or pending related boost or MAP fault codes

What to check

  • Read and record U068B and any other related DTCs, including network U-codes and P-codes
  • Check live data for inlet pressure, turbo boost and related sensors for missing or frozen values
  • Inspect sensor connector and wiring harness visually for damage, corrosion, breaks or water ingress
  • Verify sensor supply (reference) voltage and ground at the sensor connector with key ON
  • Check for expected communications on vehicle network with a scan tool or CAN/LIN monitor
  • Perform wiggle test of wiring and connector while watching live data or communication status

Signal parameters

  • Analog-style pressure sensors: signal typically 0.5–4.5 V proportional to inlet pressure (vacuum to boost) — verify vehicle-specific range
  • Reference voltage to sensor commonly 5 V (verify on vehicle) and good low-resistance ground
  • Digital / networked sensors: regular message updates on vehicle network (message rate varies by vehicle, typically several Hz); absence = lost communication
  • No communication, open circuit (near 0 V) or short to battery/ground are fault indicators; check for voltage outside expected range

Diagnostic algorithm

  1. Verify DTC: use a capable scan tool to confirm U068B and note freeze frame and any other stored network or sensor codes.
  2. Check related modules: query other modules for similar communication errors — isolating whether the problem is sensor-side or bus-wide.
  3. Inspect harness/connectors: visually inspect and flex the harness at the sensor and at junctions for damage, corrosion, loose pins or moisture.
  4. Verify power/ground: back-probe the sensor connector with key ON and measure reference voltage and ground continuity to chassis ground. Repair any missing or out-of-range supply/ground before continuing.
  5. Check signal: with the engine running (if safe) or using appropriate test mode, monitor the sensor’s signal line (analog) or the network message (digital) using a scan tool or oscilloscope. Look for expected voltage swing or periodic messages.
  6. Network check: if the sensor is networked, check CAN/LIN bus health (termination resistance ~60 ohm for CAN, bus idle voltage levels) and scan for bus-off or error-counter symptoms. Repair any bus issues.
  7. Wiggle and reproduce: while observing live data or bus messages, wiggle connectors/wiring to find intermittent faults.
  8. Isolate component: if wiring and power/ground are confirmed good but no valid signal/communication, replace the pressure sensor or sensor module. Re-scan and test drive.
  9. Reprogram/initialize: if a new sensor or module is installed, perform any required calibration or programming per manufacturer procedure.
  10. Final verification: clear codes, perform functional test of boost control and a road test, then recheck for reappearance of U068B or related codes.

Likely causes

  • Damaged connector or corroded pins at the sensor
  • Broken or shorted signal/reference wire between sensor and module
  • Failed pressure sensor electronics
  • CAN/LIN bus error or module not transmitting
  • Missing sensor power/ground due to blown fuse or connector issue

Fault status

⚠️ Status
Lost Communication With Turbocharger/Supercharger Inlet Pressure Sensor A — control module not receiving valid sensor data or periodic messages.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-3.0 hours

Similar codes

U0100 U0121 U0155 U0073 U0401 P0236
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