My bulletproof 199,150 mile '12 Prius II CEL came on 2 days ago, the dreaded P0302. Oil level mark on the dipstick was nonexistent. I was due for an oil change. Coolant level was 1" below low mark. A few finely black speckled dots visible in coolant, although still very pink. The kicker: the harness leading from the ignition coils to the left and downside the rear of the engine was caked on with oil and dirt. The debris starts right about where the head meets the block and it's heavy, completing coating the 3 connectors at the bottom of the block (oil pressure, crank position, and O² sensor). That left corner of the engine is completely caked on with black soot, grime, dirt. The real kicker: I've taken my car in for the inverter recall around 150k. I specifically remember asking them if they changed the coolant in the process. In my haste, I've failed to realize the engine and inverter coolant are 2 totally separate systems! Bonehead move. Now I've got 3 days to get this puppy back on the road. I've done a head gasket and timing belt on a prior car, a '96 Civic, so I have some wrenching experience. Will also, while I have the engine apart, clean the egr, intake, pcv, and whatever else I've heard thrown around on here since I initially purchased my '04 Prius. So for anyone reading this, learn from my obvious blunder. As maintenance free as these cars are, they're not bulletproof.