🚨 Diagnostic Profile
Vehicle Make: Buick
Technical Description: IC Cylinder 2 Not Toggling After Enable
This code indicates that the Engine Control Module (ECM) has commanded Cylinder 2 to activate or deactivate (toggle) as part of an Active Fuel Management (AFM) or Dynamic Fuel Management (DFM) cycle, but the cylinder has failed to respond to this command. This is typically caused by a faulty lifter solenoid, oil pressure control valve, or wiring issue within the cylinder deactivation system.
🚨 Repair Difficulty Tier
Difficulty Rating: Intermediate
This repair requires a capable OBD-II scanning tool to read live data and bi-directional controls for the AFM/DFM system. While it does not involve high-liability systems like airbags, it does require mechanical disassembly of the valve cover and intake components, along with electrical diagnostic knowledge to test solenoid resistance and oil pressure feeds. Basic DIYers may struggle with the precision needed for lifter inspection and solenoid replacement.
🛠️ Resolution Steps
Step 1: Preliminary Inspection
Begin by visually inspecting the wiring harness connector leading to the Cylinder 2 AFM solenoid for any signs of corrosion, chafing, or disconnection. Check the engine oil level and quality, as low oil pressure or dirty oil is a common cause of lifter toggle failures. Verify that the oil filter is OEM-spec, as aftermarket filters sometimes restrict the oil flow required for solenoid actuation.
Step 2: Diagnostic Verification
Connect an OBD-II scanner capable of bi-directional controls to the vehicle. Navigate to the AFM/DFM live data stream and attempt to manually toggle Cylinder 2 using the bi-directional command. Use a multimeter to check the resistance of the Cylinder 2 solenoid (compare against OEM specifications, typically 4-6 ohms) and verify battery voltage (12V+) is present at the connector during the toggle command. Additionally, perform an oil pressure test at the AFM solenoid gallery to ensure adequate pressure (usually requires 15-20 PSI minimum for actuation).
Step 3: Resolution & Reset Process
If the solenoid fails the resistance test or oil pressure is insufficient due to a stuck valve, remove the valve cover to access the lifter assembly. Replace the faulty AFM solenoid and/or the specific lifter for Cylinder 2 if it shows signs of mechanical sticking or wear. Once replaced, clear the Diagnostic Trouble Codes (DTCs) using the scan tool and perform an ECM relearn/reset procedure. Conduct a test drive under varying throttle loads to confirm the AFM system properly transitions between V4 and V8 modes without triggering the code again.
📦 Parts, Labor, and Budget Estimates
Required Components/Software:
- AFM/DFM Lifter Solenoid (Cylinder 2 specific)
- Lifter Oil Manifold Assembly (LOM) if pressure issues are found
- Valve Cover Gasket Set (required for disassembly)
- Bi-directional OBD-II Scan Tool (e.g., Snap-on, Autel, or GM-specific MDI)
Average Component Price: $45 – $150 for a single solenoid; $250 – $450 for a full Lifter Oil Manifold replacement if required.
Estimated Labor Hours: 2.5 – 4.0 hours (Book time includes valve cover removal, lifter/solenoid replacement, and system reset/verification).