P0341 and P0344: camshaft sensor range and intermittent signal

The camshaft position sensor tells the ECU which stroke each cylinder is on, which is what makes sequential injection and coil-on-plug ignition possible. The crankshaft sensor knows the angle; the camshaft sensor knows the phase.

Code	Meaning
P0340	Camshaft position sensor A circuit
P0341	Range/performance
P0342	Circuit low
P0343	Circuit high
P0344	Circuit intermittent

Background: P0340 camshaft position sensor diagnostics.

P0341 versus P0344

P0341 — the signal is present but its relationship to the crankshaft is not what the ECU expects. That is a timing statement, and it may not be about the sensor at all.

P0344 — the signal comes and goes. That is almost always a connection.

The two need different investigations, and conflating them wastes time.

When P0341 is really a timing problem

The ECU calculates the phase between crank and cam signals. If the camshaft is physically in the wrong position relative to the crankshaft, the sensor reports that faithfully and the ECU flags a range fault.

Causes:

• Chain stretch. The camshaft is retarded relative to the crank because the chain is longer than it was.
• A worn tensioner allowing slack.
• A phaser stuck away from its default position: P0010 and P0013 camshaft actuator circuit.
• Timing assembled a tooth out after previous work.

If P0341 appears alongside P0016 or one of its siblings, treat it as a timing fault first. P0016 crank-cam correlation and P0017 to P0019 on bank 2.

The cold-start rattle test applies here too. One or two seconds of chain noise before oil pressure builds is the warning that the chain is the cause.

When P0344 is a connection

An intermittent signal that comes and goes with engine movement, temperature or vibration points at:

• A connector not fully latched, or with spread pins.
• Oil in the connector, which is common because these sensors thread into the head and camshaft seals leak.
• Chafed wiring where the harness passes a bracket.
• A failing sensor that drops out when hot — the heat-related version described in P0320 to P0322.

Oil in the connector deserves special attention. It wicks up the wiring by capillary action, and it can travel far enough to reach the ECU connector. Cleaning the connector without fixing the leak means it returns.

Symptoms

• Extended cranking before starting. Without the cam signal the ECU must work out phase by trial injection, which takes an extra revolution or two.
• A stall that restarts immediately.
• Rough running or a misfire that comes and goes.
• Reduced power if the ECU falls back to a batch injection strategy.
• Sometimes nothing at all — many engines run acceptably on the crank signal alone once started.

That last point is why these codes get ignored. The car drives, so the fault waits until it becomes a no-start in a car park.

Catching an intermittent

The difficulty with P0344 is that everything tests fine when you look at it.

The productive approach is to log rather than to test:

1. Leave RPM and camshaft-related PIDs logging during normal driving.
2. Note the conditions when the fault occurs — hot, cold, over bumps, at a particular speed.
3. Wiggle test with the engine running, moving the harness section by section while watching live data.
4. Compare freeze frames from multiple occurrences. Common conditions across them narrow the cause.

Diagnosing intermittent faults with OBD.

Sensor type matters for testing

Two kinds are in use:

Hall effect sensors need a supply voltage and produce a square wave. They have three wires and can be tested for supply and ground before anything else.

Inductive sensors generate their own signal and have two wires. They can be tested for resistance and for AC output while cranking.

Knowing which you have prevents chasing a supply voltage on a sensor that does not use one.

Step by step

1. Read every code. Correlation codes change the diagnosis entirely.
2. Cold-start the engine and listen for chain rattle.
3. Unplug and inspect the connector for oil and corrosion.
4. Check the harness where it passes brackets and hot surfaces.
5. Log during the fault rather than testing when it is absent.
6. Fix any oil leak that contaminated the connector, or it repeats.

Try it on the free tier of the app — pair an ELM327 adapter and leave logging running on a car with an intermittent fault. The recording of the moment it fails is worth more than any test performed while it works.