Network, generic

U02AF Lost Communication With Turbocharger Turbine Inlet Valve Position Sensor

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

In staged turbocharging a valve in the exhaust path decides how much gas passes through the small high-pressure stage and how much goes around it. GM's patent keeps this valve closed in one load and speed region, modulates it in a transition region and coordinates it with the variable vanes; Ford's two-stage patent opens the bypass fully and cuts torque when valve control is lost. Both depend on knowing the actual valve position. U02AF concerns a position sensor that sends that value digitally, for example as SENT frames, and has stopped doing so. No manufacturer documents U02AF publicly. An analog sensor would report P22D4 to P22D8 instead. CARB expects lost communication of digital inputs to set its own code. The engine typically limits boost and lights the MIL.

Likely causes

Heat-damaged connector or wiring at the sensor near the exhaust
Position sensor electronics failed
Sensor supply or ground missing
Fault at the engine controller input

Symptoms

  • Check engine lamp
  • Boost limited, sluggish response at low and medium engine speed
  • Engine in reduced-power mode

Repair estimate

DifficultyHardWorkshop job
Parts and labour€50–1,500
Time0.5–4 h

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

Parts involved

turbine inlet valve position sensorvehicle bus wiring

Related codes

P22D4P22D5P22D8P22CFU02B0

References: patents.google.com, patents.google.com, law.cornell.edu.