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U0675 Lost Communication With Turbocharger/Supercharger Speed Sensor A

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

A speed sensor in the bearing or compressor housing lets the controller watch how fast the turbocharger rotor spins, mainly to keep it below its overspeed limit; a BorgWarner patent (US9353760B2) describes such a sensor and gives that reason, and CARB names turbocharger/turbine speed among the data diesel vehicles must output. Classic sensors send a pulse train whose faults are P2578 to P2582. U0675 applies when sensor A delivers the speed as a digital message and those messages are missing or invalid. No manufacturer documents this code publicly. Without a speed value the controller cannot tell how close the rotor is to its limit, so it will usually cap boost and engine power until the fault is gone.

Likely causes

Sensor wiring near the turbocharger heat-damaged or broken
Connector loose, oily or corroded
Speed sensor electronics failed
Engine controller input or software fault

Symptoms

  • Check engine light
  • Boost and power limited
  • Noticeably weaker acceleration at higher loads

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–600
Time0.5–2.5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

turbo speed sensor avehicle bus wiring

Related codes

P2578P2579P2580P2581P2582

References: patents.google.com, law.cornell.edu, en.wikipedia.org.