U02AD code meaning
Lost Communication With Turbocharger/Supercharger Boost Control B
Network system Generic code U02xx codes Check engine light
What U02AD means
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.
U02AD at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor0.5 to 5 hours
- Clears after repairAfter a drive cycle
Symptoms of U02AD
- Check engine lamp
- Weak pull in the speed range where the second stage normally takes over
- Engine power limited
Common causes of U02AD
- Most likelyDamaged plug or harness at actuator B, heat-aged insulation
- PossibleSupply or ground of actuator B interrupted
- PossibleElectronics of actuator B failed
- Less likelyReplacement actuator not matched or not set up for position B
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Boost control module bVehicle bus wiring
What each part of U02AD means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| AD | The exact fault in that area. |
What to do next
- Note U02AD and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about U02AD
What does U02AD mean?
U02AD means "Lost Communication With Turbocharger/Supercharger Boost Control B". 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. It is a generic code, so it means the same on every make.
Is it safe to drive with U02AD?
Drive gently and only to a workshop. With U02AD the car can go into limp mode (reduced power) to protect itself.
Will U02AD fail an emissions test?
Yes, it can. U02AD is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is U02AD to fix?
Difficulty: hard. A typical repair takes 0.5 to 5 hours of work. This is a job for a workshop.
Will U02AD clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.