🚨 Diagnostic Profile
Vehicle Make: Buick
Technical Description: CKP/CMP Correlation (Crankshaft Position / Camshaft Position Correlation Fault)
This code indicates the Engine Control Module (ECM) has detected a timing misalignment between the signals received from the Crankshaft Position (CKP) sensor and the Camshaft Position (CMP) sensor. The ECM uses these two signals to calculate valve timing, fuel injection timing, and ignition spark events. A correlation fault means the two signals are out of sync with expected parameters, which can stem from mechanical timing issues (stretched timing chain, jumped tooth) or electrical/sensor faults.
🚨 Repair Difficulty Tier
Difficulty Rating: [Intermediate]
This repair typically requires a quality OBD-II scan tool capable of reading live bidirectional data (crank/cam sync graphs), a digital multimeter for sensor circuit testing, and a strong understanding of engine timing components. In cases involving a stretched timing chain, specialized timing alignment tools and more advanced mechanical disassembly knowledge are needed, pushing complexity toward the higher end of the intermediate scale. This is not a simple sensor-swap in most V6 Buick applications due to timing chain/cover access.
🛠️ Resolution Steps
Step 1: Preliminary Inspection
Begin with a visual inspection of the CKP and CMP sensor wiring harnesses for chafing, corrosion, or loose connectors near the crankshaft pulley and valve cover/timing cover areas. Check for oil contamination on sensor connectors, as oil intrusion is a common cause of signal interference on Buick 3.6L and 3.8L engines. Inspect for any recent engine work, timing chain cover gasket leaks, or signs of prior timing component replacement that could indicate a chain already began skipping.
Step 2: Diagnostic Verification
Connect a scan tool capable of displaying the Crank/Cam synchronization graph in live data mode. Compare the relative timing of the CKP and CMP waveforms against factory specification; a consistent offset points to a mechanical timing issue (stretched chain or jumped tooth), while an erratic or intermittent signal points toward a wiring or sensor fault. Use a digital multimeter to verify reference voltage (usually 5V or 12V depending on sensor type) and ground continuity at each sensor connector with the key on, engine off. Compare live CKP and CMP RPM signal values side by side; a discrepancy during cranking confirms the correlation fault.
Step 3: Resolution & Reset Process
If wiring or a failed sensor is confirmed, replace the faulty CKP or CMP sensor following OEM torque and positioning specifications. If mechanical timing is confirmed (via timing mark alignment or borescope inspection), the timing chain, tensioner, and guides must be replaced as a complete kit to prevent recurrence. After repairs, clear the DTC using the scan tool, perform a crank/cam variation relearn procedure if required by the ECM, and conduct a full drive cycle to confirm the correlation fault does not return.
📦 Parts, Labor, and Budget Estimates
Required Components/Software: CKP sensor, CMP sensor, timing chain kit (chain, tensioner, guides) if mechanically confirmed, OEM-level scan tool with bidirectional control, digital multimeter.
Average Component Price: CKP/CMP sensors typically range $40–$120 each; a complete timing chain kit for Buick V6 engines generally ranges $250–$600 depending on engine configuration.
Estimated Labor Hours: Sensor replacement alone: 0.5–1.5 hours. Full timing chain replacement (including diagnostic time): 4–8 hours depending on engine accessibility and whether the engine must be partially removed or tilted for cover access.