P0247

What Does Code P0247 Mean?

The diagnostic trouble code (DTC) P0247 signifies a malfunction within the electrical control circuit for the turbocharger/supercharger wastegate solenoid ‘B’. This code is set by the Engine Control Module (ECM) or Powertrain Control Module (PCM) when it detects an electrical anomaly within the circuit responsible for actuating wastegate solenoid ‘B’. The wastegate is a critical component in turbocharged or supercharged systems, regulating boost pressure by diverting a portion of exhaust gases away from the turbine (in turbochargers) or by controlling airflow (in superchargers). The wastegate solenoid ‘B’ is an electro-mechanical device that typically modulates vacuum or pressure signals to mechanically actuate the wastegate valve. The ECM/PCM continuously monitors the electrical characteristics of this circuit, including voltage, current draw, and resistance. If these readings deviate from the manufacturer’s specified parameters – indicating conditions such as an open circuit, a short to ground, or a short to voltage – the ECM/PCM will register P0247, illuminate the Malfunction Indicator Lamp (MIL), and potentially initiate a “limp-home” mode to prevent engine or turbocharger damage. The ‘B’ designation usually refers to a specific solenoid in a multi-solenoid system, or a secondary wastegate control in more complex setups.

Common Symptoms

• Reduced Engine Power or Acceleration: The most prevalent symptom, as uncontrolled boost pressure (either underboost or overboost) directly impacts engine performance.
• Illuminated Malfunction Indicator Lamp (MIL): The “Check Engine” light will be active on the dashboard.
• Increased Turbo Lag: A noticeable delay in power delivery after throttle input due to inadequate boost pressure generation.
• Erratic or Uncontrolled Boost Pressure: The wastegate may be stuck open or closed due to lack of solenoid control, leading to either constant underboost or potentially dangerous overboost conditions.
• Engine Entering “Limp Mode”: The ECM may deliberately reduce engine power output to protect components from potential damage.

What Causes the Code P0247?

• Faulty Turbocharger Wastegate Solenoid ‘B’: Internal electrical failure of the solenoid coil, such as an open circuit, short circuit, or high resistance.
• Wiring Harness Issues: Damaged, chafed, corroded, or open wiring within the wastegate solenoid ‘B’ control circuit. This includes shorts to ground or shorts to battery voltage.
• Poor Electrical Connections: Loose or corroded terminals at the wastegate solenoid ‘B’ connector, or at the corresponding ECM/PCM connector.
• Faulty Powertrain Control Module (PCM)/Engine Control Module (ECM): Although less common, an internal failure of the PCM’s driver circuit for the wastegate solenoid ‘B’ can cause this code.
• Vacuum Leaks or Pressure Leaks: If the solenoid controls a vacuum or pressure signal to the wastegate actuator, leaks in these lines can sometimes indirectly contribute to the ECM detecting an electrical anomaly if the solenoid attempts to compensate unsuccessfully.

How to Diagnose and Troubleshoot

Diagnosing P0247 requires a systematic approach, utilizing a digital multimeter (DMM) and an OBD-II scan tool.

1. Visual Inspection: Begin by thoroughly inspecting the wastegate solenoid ‘B’ and its entire wiring harness. Look for any signs of physical damage, such as frayed wires, burned insulation, corrosion at connectors, or loose connections. Pay close attention to areas where the harness might rub against engine components or chassis. If applicable, also inspect any vacuum or pressure lines connected to the solenoid for cracks or disconnections.
2. Retrieve Freeze Frame Data: Connect an OBD-II scan tool and retrieve any stored freeze frame data associated with P0247. This data provides a snapshot of engine operating conditions (engine RPM, vehicle speed, engine load, boost pressure, etc.) at the precise moment the DTC was set, which can offer valuable diagnostic clues.
3. Clear DTC and Test Drive: Clear the P0247 code and perform a comprehensive test drive under varying engine loads and RPMs, attempting to replicate the conditions observed in the freeze frame data. Observe if the code immediately returns.
4. Solenoid Resistance Test: Disconnect the electrical connector from the wastegate solenoid ‘B’. Using a DMM set to the ohms function, measure the resistance across the two terminals of the solenoid itself. Compare this reading to the manufacturer’s specifications (typically found in a service manual, often ranging from 10 to 30 ohms). An infinite resistance (open circuit) or a resistance very close to zero ohms (short circuit) indicates an internal failure of the solenoid.
5. Wiring Harness Continuity and Short Tests:
   • Continuity: With the solenoid disconnected and the appropriate ECM/PCM connector disconnected (refer to service manual for pinout), use the DMM to check for continuity between the solenoid connector terminals and their respective ECM/PCM connector terminals. Resistance should be very low, ideally less than 5 ohms. High resistance indicates a wiring issue.
   • Short to Ground: Measure the resistance between each wire terminal at the disconnected wastegate solenoid harness connector and a known good chassis ground. There should be infinite resistance. Any low resistance indicates a short to ground.
   • Short to Voltage: With the ignition ON (engine OFF), use the DMM to check for voltage on each wire terminal at the disconnected solenoid harness connector. Unless specified by the manufacturer for a constant power feed, there should be no voltage present on the control wire.
6. Power and Ground Supply Check: With the ignition ON, check for proper power supply (usually battery voltage or a 5V reference) and ground at the wastegate solenoid ‘B’ harness connector. One pin typically provides power, and the other is the ECM’s control/ground circuit.
7. PCM Driver Test (Advanced): If the solenoid and all associated wiring test good, the fault may lie within the PCM. This requires an advanced scan tool with bidirectional control capabilities to command the solenoid ON/OFF while monitoring voltage signals on the control circuit with a DMM or oscilloscope. If the PCM fails to provide the correct control signal, it suggests an internal PCM driver fault.

Recommended Repairs and Solutions

Once the root cause of P0247 has been accurately identified through thorough diagnostics, the appropriate repairs can be implemented:

• Replace Wastegate Solenoid ‘B’: If the solenoid itself tests faulty (open, shorted, or out of resistance specification), replacement is the most direct solution. Always use an OEM-quality or equivalent aftermarket part to ensure proper operation and longevity.
• Repair or Replace Wiring Harness: If damaged or corroded wiring is discovered, perform precise repairs. This may involve splicing in new sections of wire using appropriate connectors, heat shrink tubing, and proper crimping techniques, or replacing entire sections of the engine wiring harness if damage is extensive. Ensure all repairs are weatherproof and properly secured.
• Clean Electrical Connectors: If corrosion or poor contact is found at the solenoid or PCM connectors, carefully clean the terminals using an electrical contact cleaner and a small wire brush. After cleaning, apply a thin layer of dielectric grease to prevent future corrosion and ensure a robust connection.
• Address Vacuum/Pressure Leaks: If the solenoid controls pneumatic lines and leaks were found, replace any cracked or damaged vacuum or pressure hoses. Ensure all connections are secure.
• PCM Replacement/Reprogramming: If all other components and wiring have been meticulously verified as functional, and a PCM driver fault is definitively confirmed, then the PCM may require replacement and subsequent programming/coding to the vehicle. This is typically a very last resort due to cost and complexity.

After any repair, clear the DTCs from the ECM and perform a comprehensive test drive to ensure the repair has resolved the issue and the code does not return. Monitor live data for boost pressure and wastegate solenoid operation during the test drive to confirm proper functionality.