P0016

What P0016 means

This code means the computer is comparing the position of the crankshaft to the position of the camshaft on bank 1, and the two are not lining up the way they should. In simple terms, the engine has a timing chain (or belt, on some engines) that keeps the crank and cam turning in a fixed relationship to each other. The computer watches both with sensors, and when the timing between them drifts outside the expected window, it sets this code. It is not naming a broken part. It is naming a symptom: the timing relationship is off.

Is it safe to drive

Treat this one seriously. If the timing chain has stretched or a chain guide has failed, it can jump further out of time or break outright while you are driving. That can cause the valves and piston to collide inside the engine, which is expensive damage, not a repair. If the check engine light is flashing, or you notice rattling on startup, rough idle, hesitation, or a sudden loss of power, stop driving it and have it towed rather than driven in. If the light is steady and the car otherwise runs fine, it is usually safe for a short trip to get it looked at soon, but do not put this off for weeks.

Common causes, most likely first

On most engines the first suspect is a stretched or worn timing chain, or a chain guide or tensioner that has worn out and is letting the chain flop around. This is more common on engines with a known history of chain stretch, and less common on engines with timing belts, where a stretched belt or slipped tensioner does something similar. After that, a failing camshaft or crankshaft position sensor, or a sensor with a damaged wiring connector, can cause the same code without any real timing problem, and that fix is much cheaper. Low oil pressure or old, sludged oil can also throw off a hydraulic tensioner's ability to hold tension correctly. Which of these is likely depends on the specific engine, so we would need to know the make and model before guessing further.

What diagnosis and repair involve

Diagnosis starts with pulling up live data on the crank and cam sensors and comparing their signals, checking the wiring and connectors, and often pulling the timing cover or valve cover to physically look at the chain, guides, and tensioner for wear or stretch. That inspection labor is usually where most of the diagnostic time goes, roughly an hour or two depending on how the engine is built. If it turns out to be a sensor or a wiring issue, the repair is comparatively inexpensive, often in the neighborhood of a couple hundred dollars including parts and labor. If it is the timing chain itself, that is a much bigger job, often running well into four figures, because it usually means removing the timing cover and sometimes other components to get at the chain. We would rather find out which one it is before quoting a number, since guessing wrong in either direction does not help you.

If you want this looked at, Auto Star Service Center is open Saturdays, which helps if a weekday drop-off does not work for you.