I found this by doing a google search.( It means your camshaft and your crankshaft positions are not lined up as the computer expects. Either you have a timing issue (in which case I would not run the car until it's been diagnosed professionally) or you have serious oil flow problems.) I don't understand it, but I'm NOT a mechanic. I think Walmart screwed you when they changed the oil and didn't tighten the filter. Perhaps there's damage to the main and rod bearings now due to a lack of oil. I don't understand how low oil can change the timing on these engines, but I'm old school, not new. It appears that the low oil has changed the timing on the car. Do you also get a P0016?