Code
P00C5
Generic
P — Powertrain
Turbocharger/Supercharger B Turbine Overspeed
Views:
UK: 18
EN: 31
RU: 23
AI status
Completed
Completed
100%
Causes
- Faulty turbine speed sensor (B) or sensor mounting
- Open/shorted or intermittent wiring/connectors to the turbine speed sensor
- Faulty ECM or calibration/software error
- Wastegate or variable-geometry actuator stuck closed or not responding to commands
- Failed boost control solenoid or plumbing (vacuum/pressure leaks or blockages)
- Mechanical turbocharger failure (shaft imbalance, damaged turbine wheel, low oil supply)
Symptoms
- Malfunction Indicator Lamp (MIL)/Check Engine Light illuminated
- Reduced engine power or limp-home mode
- Erratic or excessive boost readings
- Unusual turbo whine, rattling, or grinding noises from turbo area
- Poor drivability, hesitation, or surging
- Possible excessive exhaust smoke if turbo oil seals fail
What to check
- Read DTCs and freeze-frame / stored data; note related turbo/boost codes
- Compare turbine speed (B) live data to turbine speed (A) and engine RPM
- Visually inspect wiring and connector for turbine B speed sensor
- Perform a functional check of wastegate/variable geometry actuator and boost control solenoid
- Inspect turbocharger for shaft play, damaged blades, oil leakage, or foreign object damage
- Check oil feed/drain lines and engine oil level/condition
Signal parameters
- Turbine speed sensor (B) signal: frequency (kHz) or voltage pulses — compare expected range from manufacturer
- Turbine speed (B) vs turbine speed (A) and engine RPM correlation
- Intake manifold absolute pressure / boost pressure (kPa or bar)
- Commanded vs actual wastegate/variable-geometry actuator position (percent)
- Boost control solenoid duty cycle (percent) or control voltage
- Engine oil pressure (psi/bar) at idle and under load
Diagnostic algorithm
- Retrieve all stored and pending DTCs and freeze-frame data. Note related codes (boost, actuator, sensors).
- Check ECM software version and service bulletins for known false-positives or calibration updates.
- Visually inspect turbine B speed sensor connector, wiring harness, and sensor mounting for damage, corrosion, or loose connections.
- Using a scan tool, monitor live data: turbine speed (B), turbine speed (A), engine RPM, boost pressure, wastegate/actuator position, and boost solenoid command. Look for mismatch or implausible values.
- Verify sensor signal with oscilloscope or frequency meter at the sensor harness while cranking/ running. Confirm signal amplitude, frequency, and waveform integrity. Wiggle harness to check for intermittent faults.
- Check continuity and resistance of sensor wiring back to ECM; inspect for shorts to ground or power and measure reference/power supply to the sensor if applicable.
- Command actuator and boost control solenoid using scan tool to confirm movement and functional response. Verify commanded actuator position results in expected boost and turbine speed changes.
- Perform a physical inspection of the turbocharger: check axial/radial play, blade condition, and oil leakage. Rotate shaft by hand (engine cold) to feel roughness.
- Inspect exhaust system for restrictions (collapsed pipe, clogged particulate trap) that could affect turbine behavior.
- If sensor and wiring test good but overspeed persists, consider replacing turbine speed sensor, boost solenoid, or actuator one at a time per manufacturer guidance. If mechanical damage or bearing failure is found, repair/replace turbocharger assembly.
- After repairs, clear codes and perform a controlled road/bench test while monitoring turbine speed, boost, and actuator response to verify fault is resolved.
Likely causes
- Damaged or intermittent turbine speed sensor (most common)
- Wiring/connector fault between sensor and ECM
- Actuator or boost control solenoid failure preventing wastegate opening
- Mechanical damage to turbine (foreign object damage or bearing failure)
Fault status
Status
Turbine B overspeed detected. ECM recorded turbine speed above the allowed limit for Turbocharger/Supercharger B. Check sensor, wiring, boost control, actuator, and turbo mechanical condition.
Repair difficulty: Hard
Diagnostic time: 1.5-4.0 hours
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