B1267

What Does Code B1267 Mean?

DTC B1267 indicates a detected electrical circuit failure associated with the “Right Air Intake Servo Motor” or “Right Intake Manifold Runner Control (IMRC) Motor.” This code is typically set by the Powertrain Control Module (PCM) or Engine Control Module (ECM) when it detects an abnormal electrical condition within the dedicated circuit controlling the servo motor responsible for actuating a component of the variable intake manifold system. The “right” designation typically refers to the right bank of a V-configuration engine (e.g., V6, V8, V10), implying independent control for each bank’s intake runners or flaps. The PCM monitors the current draw, voltage feedback, and/or command signal integrity to the servo motor. A circuit failure could manifest as an open circuit (no current flow), a short to ground, a short to voltage, or an out-of-range feedback signal from an integrated position sensor (such as a potentiometer or Hall-effect sensor) that does not correlate with the commanded position. The variable intake manifold system is crucial for optimizing engine breathing across the RPM range, typically by altering the effective length or geometry of intake runners to enhance low-end torque or high-end horsepower by utilizing resonant frequencies within the intake tract.

Common Symptoms

• Illuminated Malfunction Indicator Lamp (MIL): The “Check Engine” light will be on.
• Reduced Engine Performance: Noticeable decrease in power, particularly at specific engine speeds (e.g., poor low-end torque or diminished high-RPM horsepower).
• Rough Idle or Erratic Engine Operation: If the intake runners are stuck in an unfavorable position, it can lead to suboptimal cylinder filling.
• Increased Fuel Consumption: Inefficient engine operation due to compromised air intake dynamics can lead to poorer fuel economy.
• Hesitation or Stumble During Acceleration: The engine may not respond smoothly to throttle inputs.
• Audible Clicking or Grinding Noises: Mechanical noise originating from the intake manifold area, indicating a struggling or failing servo motor or binding runners.

What Causes the Code B1267?

• Faulty Right Air Intake Servo Motor: The most common cause, involving internal electrical failure (e.g., burnt windings, internal short/open circuit) or mechanical failure of the motor’s internal gears or linkages.
• Wiring Harness Damage: Open circuits, shorts to ground, shorts to voltage, chafed insulation, or corroded wiring in the harness connecting the PCM/ECM to the servo motor.
• Defective Electrical Connector: Loose terminals, corrosion, bent pins, or poor seating at the servo motor connector or PCM/ECM connector.
• Mechanical Binding of Intake Manifold Flaps/Runners: Excessive carbon buildup, debris, or physical damage within the intake manifold preventing the flaps or runners from moving freely. This mechanical resistance can cause the servo motor to overcurrent, struggle, or fail to reach its commanded position, leading to a circuit fault detection by the PCM.
• PCM/ECM Internal Fault: While less common, an internal fault within the PCM/ECM could lead to incorrect control signals, inability to monitor the circuit correctly, or improper interpretation of feedback signals.

How to Diagnose and Troubleshoot

A systematic diagnostic approach is essential to accurately pinpoint the root cause of B1267:

1. Preliminary Visual Inspection: Begin by visually inspecting the “Right Air Intake Servo Motor” and its associated wiring harness for any obvious signs of damage, chafing, corrosion, or disconnections. Check the integrity of the motor’s mounting and ensure all vacuum lines (if applicable to the system’s design) are intact and properly connected, although B1267 specifically targets an electrical circuit.
2. OBD-II Scan Tool Verification: Use a professional-grade scan tool to confirm B1267 is present and check for any other related or pending Diagnostic Trouble Codes (DTCs). Access live data parameters for the variable intake system, if available. Look for commanded vs. actual flap positions or servo motor duty cycles. If the scan tool offers bi-directional control, attempt to actuate the right intake servo motor while observing its physical movement and listening for proper operation. Monitor feedback values if present.
3. Electrical Circuit Integrity Test (Using a Digital Multimeter – DMM):
   • Disconnect the Servo Motor: Safely disconnect the electrical connector from the right air intake servo motor.
   • Power and Ground Verification: With the ignition ON (Key On, Engine Off – KOEO), use a DMM to test for proper voltage supply at the servo motor connector terminals. Consult the vehicle’s wiring diagram for specific pinouts and expected voltage (typically 12V battery voltage or a 5V reference). Also, verify a solid ground connection at the appropriate pin.
   • Continuity Test: With the ignition OFF and the PCM/ECM connector disconnected, perform continuity tests on all wires between the servo motor connector and the PCM/ECM connector. Look for open circuits (infinite resistance / OL on DMM) or shorts to ground or power. Also, check for unintended continuity between adjacent wires within the harness.
   • Servo Motor Internal Resistance Test: Measure the internal resistance of the servo motor itself across its power/ground or control terminals (consult service manual for specific values). An open circuit (OL) indicates a broken internal winding, while very low resistance could indicate an internal short. Compare readings to manufacturer specifications.
   • Feedback Signal Verification (if applicable): If the servo motor incorporates a position feedback sensor, verify its output signal to the PCM during manual actuation or via bi-directional control, ensuring it falls within specified voltage ranges.
4. Mechanical System Inspection: With the servo motor disconnected or removed, manually attempt to move the intake manifold flaps or runners that the motor controls. They should move smoothly and freely through their full range of motion without binding or excessive force. If stiffness or jamming is detected, the issue may be mechanical within the intake manifold rather than the motor itself.
5. PCM/ECM Pin Inspection: If all wiring, connectors, and the servo motor test good, carefully inspect the PCM/ECM connector pins for any signs of corrosion, bending, or poor terminal tension.

Recommended Repairs and Solutions

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

• Replace the Right Air Intake Servo Motor: If the DMM tests indicate an internal fault within the servo motor (e.g., open circuit, incorrect resistance, mechanical binding of internal gears), replacement is the most direct solution. Always use OEM or a high-quality aftermarket equivalent to ensure proper function and longevity.
• Repair or Replace Wiring Harness/Connector: If the diagnosis reveals damaged wires (chafed, cut, shorted) or a compromised electrical connector, the affected section of the wiring harness should be repaired using appropriate automotive wiring techniques (e.g., solder and heat shrink, not just crimp connectors) or replaced if damage is extensive. Clean any corrosion from connector pins.
• Clean or Repair Intake Manifold Flaps/Runners: If the mechanical components within the intake manifold are found to be binding due to carbon buildup, debris, or physical damage, the intake manifold may need to be removed, thoroughly cleaned, and potentially have its internal runner components repaired or replaced. In some cases, the entire intake manifold assembly may require replacement if the internal mechanisms are not serviceable.
• PCM/ECM Replacement: This should be considered a last resort, only after all other potential causes (motor, wiring, mechanical binding) have been thoroughly diagnosed and ruled out. PCM/ECM replacement typically requires programming or flashing to the vehicle’s specific VIN and options.
• Post-Repair Verification: After completing any repair, clear all stored DTCs using a scan tool. Perform a comprehensive test drive under varying engine speeds and load conditions to ensure the code does not return and the variable intake manifold system operates correctly throughout its intended range. Monitor live data parameters to confirm proper servo motor function and flap positioning.