P0340: Camshaft Position Sensor "A" Circuit Malfunction (Bank 1)
P0340 is the crank sensor's twin trouble, one level up the engine. The camshaft sensor tells the computer which stroke each cylinder is on, and without that information the engine either takes ages to figure itself out on start-up or gives up mid-drive. The presentation overlaps heavily with P0335, and telling them apart is exactly what the code is for.
What P0340 actually means
The crank sensor says where the engine is in its rotation; the cam sensor says which half of the four-stroke cycle it's in, because the crank turns twice per cycle and looks identical both times. The computer needs the cam signal to sequence injection and spark to the right cylinder at the right moment. When that signal is missing, noisy, or implausible, it stores P0340: Camshaft Position Sensor "A" Circuit Malfunction, Bank 1.
Can you keep driving?
Severity: 4 out of 5. Same reasoning as the crank sensor: not a damage code, a stranding code. Many engines will start and run on the crank signal alone by guessing the cam phase, which is why the car may still drive with longer cranking and the occasional stumble. Guessing has limits, and a full signal loss mid-drive stalls the engine wherever you happen to be.
What causes P0340 (most likely first)
- The sensor itself failing, frequently heat-sensitive and intermittent in exactly the pattern that maddens diagnosis: fine cold, faulty hot, fine again after lunch.
- Connector or wiring faults. The cam sensor sits high on the head where oil weeps find it; an oil-wicked connector is a classic on several engines below.
- Timing drift. A stretched chain or worn belt moves the cam wheel out of the window the computer expects, setting this code as collateral. P0016 appearing alongside is the tell.
- A damaged tone ring or wheel on the camshaft.
- Low cranking voltage from a dying battery corrupting the signal during starts, the cheap cause worth eliminating first via our battery warning-signs guide.
Symptoms you'll notice
Extended cranking, especially hot. Stalling that may or may not restart immediately. Rough running and misfire-like behaviour when the computer's guess drifts. On some cars, a tachometer that works while the engine cranks endlessly, which neatly reverses the crank-sensor signature.
What it costs to fix in Australia
| Repair | Typical cost (AUD) |
|---|---|
| Cam sensor, fitted | $120–400 |
| Connector or wiring repair | $100–300 |
| Diagnosis of intermittent fault | $100–250 |
Usually one of the cheaper stranding-risk fixes in the library, with the same buying caveat as its twin: bargain-bin sensors reintroduce intermittent faults, and intermittent is the one thing you're paying to be rid of. Inspect the connector before condemning the sensor; a $0 clean of oily pins resolves a real share of these.
P0340 on Australian cars
Astra and Barina cam sensors are a known local pattern, as are Tucson and Sportage units and the Triton's. Nissans of the Navara and Pathfinder era contribute the oil-in-connector version. Anything that's had recent timing work joins the list too, because a sensor gap set slightly wrong during a belt job produces this code on the first drive home.
Will P0340 fail rego or a roadworthy?
The lamp fails a NSW pink slip and sale-time certificates in Victoria and Queensland. A car that needs three attempts to start in front of an examiner isn't helping its case either.
How to read and clear P0340
Read everything stored, because the neighbours matter: P0340 with P0335 suggests shared wiring or supply, P0340 with P0016 drags timing into it, and P0340 alone points at the sensor and its connector. Live data showing cam and crank signals side by side is precisely the comparison that separates these faults. The full index lives in the fault code library.
P0340 FAQ
What's the difference between P0335 and P0340?
P0335 is the crankshaft sensor, without which most engines won't run at all. P0340 is the camshaft sensor, without which they run badly on a guess. The codes name the culprit so you don't have to.
Can I drive with P0340?
Often the car will, with long cranking and rough patches. Whether you should depends on your appetite for stalling somewhere inconvenient; the sensible answer is briefly and locally, then fix it.
Why is starting worse when hot?
Heat-sensitive sensor internals, the same mechanism as the crank sensor's famous pattern. Hot restarts after short stops are the hardest test a marginal sensor faces.
Could it be the timing belt or chain instead?
If timing components are old or P0016 is present, yes, and that changes the urgency. A sensor code on an engine with an overdue belt is a prompt to do the belt, not just the sensor.
Related codes: P0335 · P0016 · P0011 · Full fault code library
A fault code is a starting point, not a diagnosis. The same code can have different causes on different vehicles, and any costs shown are typical Australian ranges only. Always have the fault confirmed by a qualified mechanic before buying parts or booking repairs.