P1385

What Does Code P1385 Mean?

DTC P1385 signifies a malfunction within the Variable Cam Timing (VCT) Solenoid ‘B’ circuit or its operational performance. The Engine Control Module (ECM) or Powertrain Control Module (PCM) sets this code when it detects an electrical anomaly in the VCT Solenoid ‘B’ circuit, such as an open circuit, a short to ground, a short to voltage, or an out-of-specification resistance. Beyond electrical integrity, the ECM/PCM continuously monitors the requested camshaft position versus the actual camshaft position as reported by the Camshaft Position (CMP) sensor. If the ECM/PCM commands VCT Solenoid ‘B’ to adjust the camshaft timing, but the reported actual timing does not correspond to the commanded timing within a calibrated window, or if the solenoid fails to respond electrically as expected, the P1385 code will be stored. Solenoid ‘B’ typically refers to the exhaust camshaft VCT solenoid on engines equipped with dual VCT, or it could designate a specific bank’s secondary camshaft solenoid in multi-bank configurations. The VCT system is crucial for optimizing valve overlap, improving fuel economy, reducing emissions, and enhancing engine performance across various RPMs and loads.

Common Symptoms

• Illuminated Malfunction Indicator Lamp (MIL): The “Check Engine” light will be on.
• Reduced Engine Performance: Diminished horsepower and torque, especially during acceleration.
• Rough Idle or Stalling: Incorrect cam timing can disrupt combustion stability at idle.
• Increased Fuel Consumption: Suboptimal valve timing leads to inefficient combustion.
• Engine Hesitation or Misfire-like Symptoms: Particularly under load or during transitions.
• Emissions Test Failure: Due to increased hydrocarbon (HC) and nitrogen oxide (NOx) emissions.

What Causes the Code P1385?

• Faulty VCT Solenoid ‘B’: Internal electrical failure (open/short circuit in windings), mechanical sticking due to sludge or debris, or worn components preventing proper hydraulic flow.
• Wiring Harness Issues: Damaged, chafed, open, or shorted wiring in the VCT Solenoid ‘B’ circuit. Poor or corroded electrical connections at the solenoid or ECM/PCM.
• Low or Contaminated Engine Oil: VCT systems are hydraulically actuated. Insufficient oil pressure or sludge in the oil can prevent the solenoid from operating effectively or cause the cam phaser to stick.
• Blocked Oil Passages/Filter Screens: Debris or sludge can clog the small oil passages or integrated filter screens within the VCT solenoid or its housing, restricting oil flow.
• Faulty Camshaft Position (CMP) Sensor: While less direct, an inaccurate CMP sensor signal could lead the ECM/PCM to misinterpret actual cam timing, potentially causing P1385 if it falsely indicates a solenoid malfunction.
• ECM/PCM Malfunction: Rare, but an internal fault within the ECM/PCM’s driver circuit for the VCT Solenoid ‘B’ can cause this code.

How to Diagnose and Troubleshoot

Diagnosis of P1385 requires a systematic approach, combining visual inspection, electrical testing, and potentially advanced scanner functions:

1. Verify Code and Freeze Frame Data: Connect an OBD-II scanner to confirm P1385 is present. Record freeze frame data, which provides engine conditions (RPM, engine load, temperature, etc.) at the time the code was set. This information can be crucial for recreating the fault.
2. Visual Inspection:
   • Inspect the wiring harness leading to VCT Solenoid ‘B’ for any signs of damage, chafing, corrosion, or loose connections.
   • Check the engine oil level and condition. Low oil or excessively dirty/sludgy oil can cause VCT system malfunctions.
   • Examine the VCT Solenoid ‘B’ connector for bent pins, corrosion, or contamination.
3. Electrical Testing of VCT Solenoid ‘B’ and Circuit (with a Digital Multimeter – DMM):
   • Solenoid Resistance Check: Disconnect the VCT Solenoid ‘B’ electrical connector. Measure the resistance across the solenoid terminals. Compare this reading to manufacturer specifications (typically 6-12 ohms). An open circuit (infinite resistance) or a short circuit (near zero resistance) indicates a faulty solenoid.
   • Voltage Supply Check: With the ignition ON (engine OFF), check for battery voltage at one of the solenoid connector pins (usually the power supply wire) relative to ground. If no voltage, trace the circuit back to the fuse box or ECM/PCM.
   • Control Signal Check (ECM/PCM Ground): Reconnect the solenoid. Back-probe the control wire (ground side) at the solenoid connector while the engine is running and the VCT system is commanded active (e.g., using a bi-directional scanner to command the solenoid, or observing live data during driving). You should observe a varying ground signal (PWM) or a consistent ground when commanded ON, depending on the system design. A lack of ground signal from the ECM/PCM could indicate a wiring issue or a faulty ECM/PCM driver.
   • Check for Shorts: Using the DMM in continuity mode, check for shorts to ground or power in the solenoid’s wiring harness with the connector disconnected from the solenoid and ECM/PCM.
4. OBD-II Scanner Live Data and Bi-directional Control:
   • Monitor live data parameters for VCT Solenoid ‘B’, such as commanded vs. actual camshaft position, solenoid duty cycle, and engine RPM. Look for discrepancies.
   • Use a bi-directional scanner to perform an “Active Test” or “Output Control Test” for VCT Solenoid ‘B’. Command the solenoid ON and OFF while listening for an audible click from the solenoid and observing if the camshaft angle changes as commanded (check CMP PIDs). If the solenoid doesn’t click or the cam angle doesn’t respond, it points to a solenoid or hydraulic issue.
5. Engine Oil Pressure Verification: If all electrical checks pass, verify adequate engine oil pressure, as VCT systems rely heavily on proper oil pressure and flow.

Recommended Repairs and Solutions

Once the diagnostic steps have pinpointed the root cause, the following repairs are typically recommended:

• Replace VCT Solenoid ‘B’: If electrical tests indicate an internal fault within the solenoid (incorrect resistance, no internal continuity) or if it fails the active test, replacement is the primary solution. Ensure to use an OEM or high-quality aftermarket solenoid to guarantee proper function and longevity.
• Repair or Replace Wiring Harness: If damaged, chafed, open, or shorted wiring is identified, repair the specific section using appropriate automotive wiring repair techniques (soldering, heat shrink) or replace the entire harness segment if damage is extensive. Clean and secure all electrical connectors.
• Perform an Engine Oil Change: If the engine oil is low, dirty, or sludgy, perform an oil and filter change using the manufacturer-specified oil viscosity and type. In cases of severe sludge, an engine flush may be necessary, followed by another oil change. Advise the vehicle owner on proper oil change intervals.
• Clean or Replace Oil Control Valve (OCV) Filter Screen: Some VCT solenoids or their housing have small filter screens to prevent debris from entering the solenoid. If accessible, these should be inspected and cleaned or replaced if clogged.
• Address Engine Oil Pressure Issues: If diagnostics reveal insufficient engine oil pressure, the underlying cause (e.g., worn oil pump, clogged oil pickup, worn bearings) must be addressed.
• Clear DTC and Verify Repair: After any repair, clear the DTCs from the ECM/PCM and perform a test drive under various engine conditions to confirm the repair and ensure the P1385 code does not return. Monitor live data during the test drive to verify VCT system operation.