What it means
The control module detected boost pressure above 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
- The engine or gearbox may go into limp mode
How it works
The boost control system regulates pressure from turbocharger or supercharger B, while the control module compares measured boost with its target and calibrated limit. P02CA sets when boost from unit B rises above that limit; a wastegate or variable-geometry turbine mechanism that cannot open enough can contribute.
Common causes
Most likely first.
- Wastegate stuck closed
- VGT vanes stuck closed
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 establish when turbocharger or supercharger B exceeded its target.
- Inspect the intake and charge-air plumbing for disconnected hoses, damage, or signs that could affect the boost reading or control.
- Check the boost pressure sensor and its wiring and connector for contamination, damage, or an implausible signal.
- Inspect the control hoses, actuator linkage, and electrical connections for turbocharger or supercharger B for sticking, leaks, or disconnection.
- Test wastegate or variable-geometry vane movement and boost-control operation using the manufacturer's procedure.
Common fixes
- Reconnect or replace damaged boost-control hoses and electrical connections.
- Repair or replace a faulty boost pressure sensor or its wiring if testing confirms a bad signal.
- Free or repair a sticking wastegate or actuator if the mechanism is serviceable.
- Repair or replace a turbocharger B with stuck variable-geometry vanes if testing confirms the fault.
Can I keep driving?
Because overboost can trigger limp mode and put excessive stress on the engine or turbocharger, avoid hard acceleration and stop if the engine behaves abnormally, smokes heavily, or makes unusual noises. Arrange prompt diagnosis; do not continue driving if power loss or smoke is severe.
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.