U02ADLost Communication With Turbocharger/Supercharger Boost Control B
- Generic OBD-II code · Network
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- A second boost actuator appears on engines with two chargers, either one per cylinder bank or in a staged layout where a high-pressure and a low-pressure stage share the work. BorgWarner's two-stage patent describes a valve that shifts exhaust gradually from the small to the large turbine; its setting decides which stage does the work. U02AD is stored when this B actuator falls silent on the bus while A may still respond. No manufacturer documents U02AD publicly. A Ford two-stage patent shows a typical failsafe: bypass valve fully open, wastegate shut and torque capped so the low-pressure charger cannot overspeed or surge, chiefly at altitude. CARB treats such actuators as monitored boost components. Expect a MIL and limited power.
- What you may notice
- Check engine lamp
- Weak pull in the speed range where the second stage normally takes over
- Engine power limited
- Likely causes
- LikelyDamaged plug or harness at actuator B, heat-aged insulation
- PossibleSupply or ground of actuator B interrupted
- PossibleElectronics of actuator B failed
- RareReplacement actuator not matched or not set up for position B
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €50 – €2,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.