What does it mean?
The complex ballet of mechanical and electrical parts in your engine make it possible to harness the power locked away in every drop of fuel injected into the cylinders. As is the case with many things in life, timing is absolutely critical. If the cylinder isn’t in the right place at the right time, you’re not going anywhere, or at least not smoothly and quietly.
Mechanically-speaking, the timing in relationship to the crankshaft and camshafts must be precise, which is the function of the timing sprockets and timing belt or timing chains. Depending on the engine, the crankshaft may be connected to the camshaft(s) by a belt or chain and dual-overhead camshafts may be connected by gears or chains.
Timing precision is absolutely necessary, not only for good engine performance, fuel economy, and emissions-reduction, but also to prevent damage to the engine itself. As the crankshaft pushes cylinder 1 up to top-dead-center (TDC) on the compression stroke, the valves for cylinder 1 should be closing, and the spark plug should be firing, for example. If timing is off by a few degrees, the results could range from poor performance and fuel economy to catastrophic engine failure.
Regarding timing, to keep the engine running properly, the engine control module (ECM) continually monitors the crankshaft position sensor (CKP) and camshaft position sensors (CMP).
If the ECM detects that CKP is ahead or behind Bank 1 CMP, either a four-cylinder engine or the V6 or V8 bank with Cylinder 1, perhaps due to a jumped timing belt tooth or a stretched timing chain, it will illuminate the malfunction indicator lamp (MIL) and set DTC P0008, “Engine Position System Performance (Bank1),” in system memory.