P0016

What P0016 means

The computer times the camshaft and the crankshaft against each other. They're supposed to stay lined up in a fixed relationship, because that's what keeps the valves opening and closing at the right moment relative to the pistons. P0016 means the computer checked that relationship on Bank 1 and found it off. It's not naming a broken part. It's reporting that the timing between those two components isn't where it should be.

Is it safe to drive

Not really, no. If the timing has actually slipped, the valves and pistons can be close enough to contact each other. On some engines that's a bent valve. On an interference engine, if the chain jumps further, it can be much worse than that. If the light is flashing, or you notice rough running, rattling from the front of the engine, or a loss of power, stop driving it and get it looked at rather than trying to nurse it home. If the light is steady and the car drives normally, it's still worth getting in soon. This isn't a code to sit on for a few weeks.

Common causes, most likely first

Timing chain stretch is the most common cause on higher-mileage engines, especially ones known for chain wear. A worn or collapsed timing chain tensioner is right behind that, and often the actual root cause even when the chain itself is fine. Camshaft or crankshaft position sensors can throw this code themselves if they're reading poorly, without any real timing problem. Low oil pressure or old, dirty oil can keep a variable valve timing actuator from moving correctly, which reads the same way to the computer. And on engines with variable valve timing, the VVT solenoid or actuator itself can fail. Which of these is likely depends a lot on the specific engine. Some engines are known for chains, others for VVT solenoids, and a shop that works on your make regularly will usually know which one to check first.

Diagnosis and rough cost

Diagnosis starts with pulling live timing data and often a scope check on the cam and crank sensor signals, then a visual check of the chain and tensioner if the data points that way. That's usually an hour or so of labor. Cost to fix depends entirely on what's actually wrong. A sensor is a comparatively small job, often a few hundred dollars parts and labor combined. A timing chain and tensioner job is a much bigger repair, often over a thousand dollars, because on most engines it means real teardown time to get to the front of the motor. We wouldn't want to quote a number without seeing which one it is, since replacing a sensor won't fix a stretched chain and replacing a chain you didn't need to is a waste of money. If you want it looked at, we're open Monday through Friday, 8 to 5.

Generic OBD-II guidance — manufacturer-specific codes and causes vary by make, so always confirm against your vehicle. A code identifies a system or condition; it does not, on its own, prove which part has failed.