🚨 Diagnostic Profile
Vehicle/Equipment Make: BUICK
Technical Description: IC Cylinder 6 Not Toggling After Enable
This diagnostic trouble condition indicates that the Engine Control Module (ECM) has commanded Cylinder 6 to deactivate as part of the Active Fuel Management (AFM) or Dynamic Fuel Management (DFM) system, but the cylinder deactivation solenoid or lifter mechanism is failing to respond (toggle) to that command. This is commonly associated with codes such as P0306 (Cylinder 6 Misfire), P0022 (Camshaft Position – Actuator Over-Retarded Bank 1), or manufacturer-specific AFM/DFM codes like P1259 or P228A. The issue usually stems from a faulty lifter oil manifold assembly (LOMA), a stuck or failed solenoid, low oil pressure to the lifter galley, or a wiring/connector fault preventing actuation.
🚨 Repair Difficulty Tier
Difficulty Rating: Intermediate to Professional Only
This repair requires a bi-directional capable scan tool to command the AFM/DFM solenoids and verify live toggle response, as well as the mechanical knowledge to access and replace lifters or the oil manifold assembly inside the valley of the engine. While basic inspection steps are Intermediate, full teardown of the intake manifold and valley cover combined with potential reflashing of the ECM/PCM pushes this toward Professional Only for most consumers.
🛠️ Resolution Steps
Step 1: Preliminary Inspection
- Visually inspect the engine oil level and oil quality — low or dirty oil is a leading cause of AFM/DFM lifter collapse failure.
- Check the electrical connector and wiring harness leading to the Lifter Oil Manifold Assembly (LOMA) for corrosion, pin damage, or looseness.
- Inspect the oil control solenoid for Cylinder 6 specifically, looking for debris blocking the oil feed galley.
- Review freeze frame data for related misfire codes (P0306) occurring simultaneously with the AFM fault to confirm correlation.
Step 2: Diagnostic Verification
- Connect a bi-directional scan tool (such as a GM-specific tool or advanced aftermarket scanner) and access AFM/DFM bi-directional controls.
- Command Cylinder 6 solenoid to activate/deactivate and observe live data toggle feedback; a non-responsive signal confirms mechanical or electrical failure.
- Use a digital multimeter to check resistance and voltage at the Cylinder 6 solenoid connector, comparing readings to OEM specification (typically 4-6 ohms resistance).
- Perform an oil pressure test at the lifter galley to rule out low oil pressure as the root cause of non-toggling.
Step 3: Resolution & Reset Process
- If solenoid resistance or wiring is out of spec, replace the Cylinder 6 AFM/DFM solenoid or full Lifter Oil Manifold Assembly (LOMA).
- If lifters are physically collapsed or stuck, replace the lifters for Cylinder 6 following OEM torque specifications upon reinstallation.
- Clear all stored DTCs using the scan tool and perform a KAM (Keep Alive Memory) reset or battery disconnect procedure to clear adaptive learning values.
- Recheck live data by re-commanding the AFM/DFM system bi-directionally to confirm Cylinder 6 now toggles properly before finalizing repair.
- Perform a test drive while monitoring live data to ensure no misfire codes return under AFM-active load conditions.
📦 Parts, Labor, and Budget Estimates
Required Components/Software: Lifter Oil Manifold Assembly (LOMA), AFM/DFM solenoid (Cylinder 6 specific), replacement lifters (if applicable), intake manifold gasket set, valley cover gasket, bi-directional scan tool with OEM-level AFM/DFM access.
Average Component Price: $150 – $450 for the Lifter Oil Manifold Assembly; $300 – $700 if full lifter replacement for Cylinder 6 is required; diagnostic scan tool access typically included in standard shop diagnostic fee.
Estimated Labor Hours: 3.5 – 6.0 hours for full diagnostic, intake/valley cover removal, component replacement, and reassembly, depending on engine platform and accessibility.