P02CA
Turbocharger/Supercharger B Overboost Condition.
- Generic
- Powertrain
- Generic code
- Medium severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 2
- AreaFuel and air metering (injector circuit)
- CA
- FaultThe specific fault in that area
What it means
P02CA is the generic code for a Turbocharger or Supercharger B overboost condition. The engine control unit has seen actual boost pressure on the second (B) charging device, usually the second turbo on a twin-turbo or compound set-up, higher than the target it commanded for a set period. Which turbo counts as 'B' and how it is controlled depends on the model and engine.
Symptoms
- Engine warning light on
- Car enters limp-home mode with reduced power
- Sudden surge or uneven power delivery under load
- Whistling, fluttering or blow-off noises from the intake
- Possible fuel cut or hesitation at high load
- Poor fuel economy
Possible causes
- Wastegate or boost control actuator on the B turbo stuck, seized or out of adjustmentlikely
- Variable geometry vanes sticking closed due to carbon build-up, or a faulty vane actuatorlikely
- Faulty boost control solenoid, or leaking or blocked vacuum or pressure lines to the actuatorlikely
- Faulty boost pressure sensor or MAP sensor giving false readings, or wiring and connector faults on itpossible
- Wastegate or diverter valve linkage damaged, or an electric actuator failingpossible
- Restricted exhaust, such as a blocked catalytic converter or particulate filter, causing abnormal boost controlpossible
- Outdated or faulty engine control unit software where the manufacturer has a known fixrare
How to diagnose
- Read all stored and pending codes and the freeze frame data, noting load, rpm and boost at the time of setting.
- Check for related codes on the other turbo, boost sensors, actuators or the air system, and fix those first.
- Inspect the intake and boost hoses, vacuum lines and electrical connectors on the B turbo and its actuator for damage, disconnection or blockage.
- Compare live commanded and actual boost on both turbos during a safe road test and note when actual exceeds target.
- Test the boost control solenoid and actuator for correct operation and free movement, following the manufacturer's procedure for that engine.
- Check the boost pressure and MAP sensor readings against known good values with the engine off and during a load test.
- Check the wastegate or vane linkage for seizure, carbon build-up or excessive play.
- Check for exhaust restriction by checking back pressure or exhaust-related data, where the model allows.
How to fix
- Free off, clean or replace the seized wastegate or variable geometry mechanism, or replace the turbo if it is damaged.
- Replace the faulty boost control solenoid or actuator and set it up as the manufacturer specifies.
- Repair or replace leaking, split or blocked vacuum and pressure lines.
- Replace the faulty boost or MAP sensor, or repair the damaged wiring or connector.
- Repair the cause of any exhaust restriction.
- Fit an updated engine control unit calibration only if the manufacturer lists it as a fix for this fault.
Can I keep driving?
Medium severity
The car can usually be driven gently for a short time, often in limp mode, but overboost can damage the turbo and engine, so get it checked soon. Avoid heavy loads, and stop driving if power surges, noises worsen or smoke appears.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.