P0016 Code: Crankshaft / Camshaft Position Correlation (Bank 1)

What happens if you don't fix it

Symptoms you can actually notice

• Rattle at startup
• Rough running
• Hard start
• Loss of power

What the computer is actually complaining about

The crank sensor counts the teeth on the crank reluctor. The cam sensor reads a target on the camshaft. The ECU expects those two signals at a fixed offset, because the chain ties them together. When the chain stretches or jumps one tooth, the offset drifts. The ECU compares the measured offset against its stored value and sets the code once the error passes a threshold on a warm idle.

Most likely causes, cheapest check first

What you need in your hands

• OBD-II scanner with live data

  Any $25 Bluetooth reader plus a free app shows cam and crank correlation. On many cars you can watch the offset in degrees.

• Oil and filter for a change

  A $35 to $60 jug plus filter, in the grade printed on the oil cap. Fresh oil is the cheapest test for a sticky tensioner.

• Mechanic's stethoscope Optional

  $10 at a parts store. Touch the probe to the timing cover and you can hear chain slap apart from injector tick.

• Timing chain kit Optional

  Runs $150 to $400. A tensioner alone is $40 to $90, and on some engines the tensioner is the whole fix.

Test it yourself, step by step

Do these in order. Each step tells you what to do, what to look at, what counts as fine, what counts as broken, and what you will actually see.

1. 1 Plug the scanner into the port under the dash on the driver side, above your left knee. Start the engine cold and open live data. Look for camshaft and crankshaft correlation, cam retard, or VVT offset, depending on what your app calls it.

   Look at

   The offset number at idle, and whether it changes as the engine warms from cold to full temperature.

   Fine if

   The offset holds inside about plus or minus 5 degrees from cold idle to hot idle and does not drift while you watch.

   Broken if

   The offset sits past 10 degrees, or it swings wider as the engine warms. A chain that moves with temperature is stretching.

   What you'll see A degree number on the screen that stays near zero at first and then wanders as the engine heats up. Write down both numbers.

2. 2 With the engine cold, stand at the front of the car with the hood open and have someone start it. Listen at the front of the engine, behind the plastic timing cover on the passenger side where the belt runs.

   Look at

   A dry rattle for the first two seconds after the starter catches, and whether it fades as oil pressure builds.

   Fine if

   A smooth even hum with no rattle, and no tick that speeds up with the engine.

   Broken if

   A rattle or chain-slap sound in the first two seconds that fades once oil pressure comes up. That is a loose chain, and it is the stop sign.

   What you'll see A short clatter right after the starter engages, like a handful of bolts shaken in a can, then silence. No clatter is good news.

3. 3 Pull the oil dipstick out of the tube on the front of the engine, the one with the yellow loop handle. Wipe it, push it back in fully, pull it again and read the level. Then rub the oil between two fingers.

   Look at

   Where the film sits between the low and full marks, and whether the oil feels gritty or smells burnt.

   Fine if

   The level sits at or near the full mark and the oil feels slippery with no grit.

   Broken if

   The level is below the low mark, or the oil is black and gritty. Low dirty oil starves the tensioner and lets the chain slap.

   What you'll see A thin brown film at the full mark on a clean dipstick. Grit you can feel between your fingers means the chain is already wearing metal.

4. 4 Drain the old oil from the pan bolt underneath the engine, behind the front bumper cover, and fit a new filter on the front or side of the block. Fill with the grade on the oil cap, then run the engine two minutes and recheck the level.

   Look at

   Whether the startup rattle gets shorter or disappears after a fresh oil change and two cold starts.

   Fine if

   The rattle is gone or much shorter on the next cold start, and the offset number on the scanner has moved closer to zero.

   Broken if

   The rattle is unchanged and the offset still sits past 10 degrees. A fresh fill did not free the tensioner, so the chain is the suspect.

   What you'll see A cold start with no clatter, or a much shorter one. Cut the old filter open and look for brass or silver flakes in the pleats.

5. 5 Check the cam sensor plug on the top of the valve cover, at the front or rear of the head depending on the engine. Pull it, look for green crust or a pushed-back pin, and check the harness where it bends near the timing cover.

   Look at

   The condition of the pins, and whether the offset reading jumps when you wiggle the harness by hand.

   Fine if

   Clean pins, an intact loom, and an offset number that holds steady while you move the wires.

   Broken if

   Corrosion at the pins or a number that jumps when you tug the loom. A bad cam signal fakes a correlation fault for free.

   What you'll see Bright pins and a steady number on the screen. Any twitch while your hand moves the wire means the fault is in the loom.

6. 6 If the rattle and the offset both survive the oil change, stop driving it and book the chain job. A shop pulls the front cover, sets the crank and cam marks, and fits the kit with a new tensioner and guides.

   Look at

   The offset reading after the repair, taken at hot idle, plus a cold start with the hood open.

   Fine if

   The offset sits inside 5 degrees at hot idle and there is no rattle on the first cold start after the work.

   Broken if

   The offset is still off after a new chain. The tone ring or the phaser is the remaining suspect, and the shop owns that diagnosis.

   What you'll see A cold start with no clatter at all, and a scanner number near zero that stays there through a full warm-up cycle.

What the repair costs

Reference range compiled from 3 source type(s), as of 2026-11. This is not a quote — actual cost depends on your vehicle, region, and which part turns out to be the real cause.

Basis: editorial reference range, not a live parts quote · Data as of 2026-11

How to confirm it's really fixed

✓ After a chain job, do a cold start with the hood open and listen for two seconds. Then read the cam and crank offset at hot idle. It should sit inside 5 degrees and hold there through a full warm-up. If the code stays off for 100 miles of mixed driving with no rattle, the repair held.

Common questions