P0246

What Does Code P0246 Mean?

The diagnostic trouble code P0246 signifies that the Powertrain Control Module (PCM) or Engine Control Module (ECM) has detected an electrical fault in the control circuit for the Turbocharger/Supercharger Wastegate Solenoid “A”. Specifically, the “High” designation indicates that the voltage reading on this circuit is consistently above the manufacturer’s specified operational range. In most forced induction systems, the wastegate solenoid is a Pulse Width Modulated (PWM) device, which the PCM uses to regulate the amount of exhaust gas bypassing the turbocharger turbine, thereby controlling boost pressure. A “high” signal condition typically points to an open circuit on the control (ground) side of the solenoid circuit, a short to voltage, or an internal fault within the solenoid itself causing excessive resistance or an internal short to power. This prevents the PCM from effectively modulating the wastegate, potentially leading to incorrect boost pressure regulation – either overboost or underboost, depending on the wastegate’s default mechanical position and the specific electrical failure mode.

Common Symptoms

• Malfunction Indicator Lamp (MIL) Illumination: The “Check Engine” light will be activated.
• Reduced Engine Power: The vehicle may enter a “limp home” mode, significantly limiting engine output, especially under acceleration.
• Poor Acceleration/Hesitation: Noticeable lack of power during acceleration due to improper boost pressure.
• Overboost Condition: In some cases, a high voltage signal could prevent the wastegate from opening, leading to excessively high boost pressure (less common for a “high” signal fault unless it implies a stuck-closed condition).
• Underboost Condition: More commonly, if the solenoid cannot be activated, the wastegate may remain partially or fully open, preventing the turbocharger from building adequate boost.
• Unusual Noises: Potential for turbocharger whine, wastegate fluttering, or other abnormal noises from the forced induction system.
• Increased Fuel Consumption: Inefficient engine operation due to incorrect boost levels.

What Causes the Code P0246?

• Faulty Turbocharger Wastegate Solenoid: An internal electrical fault within the solenoid, such as an open circuit in the coil, a short to its internal power supply, or excessive internal resistance, causing the PCM to detect a high voltage.
• Wiring Harness Issues:
  • Short to Voltage: The wastegate solenoid control wire is inadvertently contacting a constant power source (e.g., 12V), leading to a high voltage reading.
  • Open Circuit: A break or discontinuity in the solenoid’s control (usually ground) wire or power supply wire, preventing proper current flow and resulting in a high impedance detection by the PCM.
  • Corroded or Loose Connectors: Compromised electrical connection at the wastegate solenoid or the PCM connector, leading to high resistance and an apparent high voltage reading.
• Faulty Powertrain Control Module (PCM/ECM): While rare, an internal malfunction within the PCM’s driver circuit for the wastegate solenoid can cause it to improperly apply or read voltage on the circuit.

How to Diagnose and Troubleshoot

Diagnosing P0246 requires a methodical approach using a digital multimeter (DMM), an advanced OBD-II scanner with live data and bi-directional control capabilities, and thorough visual inspection.

1. Visual Inspection:
   • Begin by visually inspecting the turbocharger wastegate solenoid “A” and its associated electrical connector and wiring harness. Look for obvious signs of damage, such as frayed wires, exposed conductors, melted insulation, corrosion at terminals, or loose connections.
   • Verify the mechanical linkage of the wastegate actuator moves freely without binding or excessive play. Ensure any vacuum or pressure lines connected to the wastegate actuator or solenoid are intact and properly routed.
2. OBD-II Scanner Data Analysis:
   • Connect an advanced OBD-II scanner and retrieve all stored and pending DTCs. Note any related codes that might provide additional context.
   • Monitor live data parameters related to the turbocharger system, specifically “Wastegate Solenoid Duty Cycle” or “Commanded Wastegate Position,” and “Boost Pressure Sensor” readings. Observe if the commanded values align with the actual operational state.
   • If available, use the scanner’s bi-directional control function to actuate the wastegate solenoid. Listen for an audible click from the solenoid and observe if the wastegate actuator arm moves. While actuating, monitor the solenoid circuit voltage feedback on the scanner for abnormal readings.
3. Digital Multimeter (DMM) Testing:
   • Solenoid Power Supply: With the ignition ON (engine OFF), back-probe the power supply wire at the wastegate solenoid connector. You should measure battery voltage (approx. 12V). If no voltage, trace back to the fuse box or PCM for an open circuit or blown fuse.
   • Solenoid Resistance Check: Disconnect the wastegate solenoid’s electrical connector. Using the DMM set to ohms, measure the resistance across the two terminals of the solenoid itself. Compare this reading to the manufacturer’s specification (typically 10-30 ohms). An open circuit (infinity or OL) or a resistance reading significantly outside specifications indicates an internally faulty solenoid.
   • Control Circuit Voltage Check: Reconnect the solenoid. Back-probe the control (signal/ground) wire at the solenoid connector. With the ignition ON and engine OFF, you might read near battery voltage if the PCM controls the ground side and isn’t actively grounding it. Start the engine and command the solenoid ON/OFF with your scanner (or observe under varying engine loads). If the PCM grounds the solenoid, you should see the voltage on the control wire drop significantly (towards 0V) when the solenoid is commanded ON. A persistently high voltage (near battery voltage) when the solenoid should be active indicates an open ground circuit from the PCM, a short to voltage on the control wire, or a faulty PCM driver.
   • Continuity Check (Wiring): Disconnect both the wastegate solenoid connector and the PCM connector. Use the DMM set to continuity or ohms (lowest range) to test for continuity between the corresponding pin on the PCM connector and the solenoid connector for both the power and control wires. There should be very low resistance (near 0 ohms). Also, check for continuity to ground and to battery voltage (by touching the test lead to a known good ground/power source) from each wire. Any continuity to ground or power on a signal wire (when not expected) or an open circuit indicates a wiring fault.

Recommended Repairs and Solutions

Based on the diagnostic findings, the following repairs are typically recommended:

1. Replace Turbocharger Wastegate Solenoid: If the DMM tests confirm an internal electrical fault (incorrect resistance, open circuit, or short) within the wastegate solenoid itself, replacement is the most common solution. Ensure the replacement part is an OEM equivalent or higher quality to maintain proper system function.
2. Repair or Replace Wiring Harness: If diagnostic tests identify an open circuit, short to voltage, or excessive resistance in the wiring harness connected to the wastegate solenoid, the affected section of the wiring must be repaired or replaced. Use high-quality, weather-sealed connectors and soldering techniques if splicing wires. Pay close attention to areas where wiring passes through bulkheads or near hot engine components, as these are common points for damage.
3. Clean or Repair Connectors: If corrosion, bent pins, or loose terminals are found at either the wastegate solenoid connector or the PCM connector, thoroughly clean the contacts with an approved electrical contact cleaner and a small brush. If pins are severely damaged, replace the connector housing and terminals as needed.
4. PCM/ECM Replacement (Rare): Only consider PCM replacement after all other potential causes, including the solenoid and the entire wiring harness, have been meticulously tested and ruled out. PCM replacement often requires specialized programming or flashing with the vehicle’s specific calibration, which typically necessitates dealership-level tools.

After any repair, clear the DTCs from the PCM using an OBD-II scanner. Then, perform an extended test drive under various engine loads and speeds to confirm that the code does not return and that the turbocharger boost control system operates correctly. Monitor live data during the test drive to verify proper wastegate solenoid operation and boost pressure regulation.