What it means
The control module detected boost pressure below its calibrated limit for turbocharger or supercharger B. The cause cannot be determined from this code alone.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The boost control system regulates pressure from turbocharger or supercharger B, and the control module compares measured boost with its target. P02CB sets when unit B produces less boost than the calibrated limit under the conditions monitored; a stuck-open wastegate or leaking charge-air pipe can be among the causes.
Common causes
Most likely first.
- Wastegate stuck open
- Charge-air pipe leak
Symptoms
- Check engine light on
- Significant power loss / limp mode
- Possible blue or black smoke from exhaust
- Whistling or hissing sound from intake
How to diagnose it
- Record freeze-frame data and compare commanded with measured boost to see when turbocharger or supercharger B failed to reach its target.
- Inspect the charge-air pipes, couplers, and clamps for splits, loose connections, or oil traces that can reveal a boost leak.
- Check the boost pressure sensor connector and wiring, and compare its reading with other available engine data for plausibility.
- Inspect the wastegate actuator, control hoses, and linkage for disconnection or movement that leaves the wastegate open.
- If no obvious leak or control fault is found, test charge-air system sealing and boost-control operation using the manufacturer's procedure.
Common fixes
- Tighten loose charge-air connections or replace a split pipe or damaged coupler.
- Reconnect or replace a damaged wastegate control hose or linkage.
- Repair the boost pressure sensor circuit if testing identifies a signal fault.
- Repair or replace a wastegate or actuator that fails its operation test.
Can I keep driving?
If the engine has reduced power, avoid overtaking, steep climbs, and towing, and get the fault checked soon. Stop if smoke is heavy, the engine overheats, or the power loss makes it unsafe to keep pace with traffic.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.