What are the most common causes of P0340?

The most common causes are: Failed camshaft position sensor; Oil-soaked or corroded sensor connector; Damaged wiring to the sensor; Timing belt or chain jumped or stretched; Engine computer fault (rare).

How much does it cost to fix P0340?

Typical US independent-shop repair cost for P0340 runs about $120 - $1,200, depending on the root cause. Common fixes: Replace the camshaft position sensor (about $120 - $400 at a shop); Repair the sensor connector and wiring (about $100 - $300 at a shop); Correct cam timing (timing belt or chain) (about $500 - $1,200 at a shop).

Will P0340 clear itself?

No, not on its own. P0340 will keep coming back every time the relevant monitor re-runs until the underlying cause is actually repaired - clearing it with a scan tool without fixing what triggered it only delays the light coming back on.

P0340: Camshaft Position Sensor A Circuit Malfunction (Bank 1 or Single Sensor)

P0340 quick answer

P0340 means the camshaft position sensor signal is missing or invalid. Check the connector and wiring, then replace the cam sensor; if the code returns, have the cam timing checked.

Severity: Moderate
Can I drive? Usually for a short distance. Many engines keep running on the crankshaft sensor with a cam sensor fault, but starting may be slow and some go into reduced power.
Typical fix: $120 - $1,200

Also written as PO340 or P340 or P 0340.

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What P0340 means

P0340 means the engine computer is not getting a valid signal from the camshaft position sensor. The computer uses it to know which cylinder is on compression so it can time injectors and coils. Many engines still run on the crank sensor alone but may start slowly or run rough. Wiring, a connector, or cam timing can cause it as well as the sensor itself.

Symptoms of P0340

Check-engine light on
Long cranking or hard starting
Rough running or reduced power
Stalling in some cases
Poor fuel economy

Is it safe to drive with P0340?

Usually for a short distance. Many engines keep running on the crankshaft sensor with a cam sensor fault, but starting may be slow and some go into reduced power. If the engine stalls, will not restart, or rattles from the timing area, stop driving and have it checked, since timing trouble can cause engine damage.

What the P0340 fix costs

Fix	DIY parts	At a shop
Replace the camshaft position sensor	$20 - $120	$120 - $400
Repair the sensor connector and wiring	$10 - $50	$100 - $300
Correct cam timing (timing belt or chain)	$100 - $400	$500 - $1,200

Ranges are rounded and for the US market only - actual price depends on region, shop labor rates, and the exact make and model.

Parts that commonly fix P0340

Camshaft position sensor - Cause #1: the sensor or its connector. Match bank and intake/exhaust position to the code
Digital multimeter - Checks the sensor supply, ground and signal before you buy one
OBD-II scanner - Reads and clears codes, and shows live data so you fix the cause rather than the symptom

Most of these open an Amazon search - add your year, make and model, because most of these parts are fitment-specific. A few link straight to the exact tool or part we have verified, because it fits any vehicle.

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What P0340 actually means

P0340 means the engine computer is not getting a valid signal from the camshaft position sensor, circuit A, bank 1 or single-sensor. The computer uses the cam sensor to know which cylinder is on its compression stroke, so it can fire the right injector and coil at the right moment. Many engines will still run on the crankshaft sensor alone, but they may start slowly, run rough, or go into a reduced-power mode. P0340 is an electrical circuit code, so the cause is often wiring or a connector, not only the sensor - and on engines with a timing belt or chain, a timing problem can trigger it too.

How to diagnose P0340 step by step

Step 1: Check the connector and wiring at the cam sensor The cam sensor is usually on the cylinder head or timing cover. Unplug it and look for oil inside the connector, corroded pins, or a harness rubbed through against a bracket. Oil in the connector usually means the sensor O-ring is leaking and wicking oil up the wire - fix the leak along with the sensor.
Step 2: Look for companion codes If P0340 appears with P0016, P0017, or other cam-crank correlation codes, the problem may be timing, not the sensor. If it appears alone, the circuit and sensor are the likelier cause. Crank sensor codes set at the same time point at a shared power or ground feed.
Step 3: Test power, ground, and signal Most cam sensors are three-wire. With the key on, check for the reference voltage and a good ground at the connector. Then back-probe the signal wire while cranking - it should switch on and off. No reference voltage means a wiring or computer fault; good power with no switching signal means replace the sensor.
Step 4: Try a quality replacement sensor If the circuit checks out and the signal is missing or erratic, replace the cam sensor with an OEM or reputable-brand part for your engine and a new O-ring. Clear the code and drive through several warm-ups. A code that stays gone confirms the sensor; one that comes back sends you to timing.
Step 5: Verify cam timing if the code returns A timing belt that has jumped a tooth or a stretched timing chain can move the cam signal enough to set P0340 even with a good sensor. Check the timing marks, or have a shop compare cam and crank signals on a scope. Correct timing is essential before any more sensors are bought.

The most common P0340 misdiagnosis

The P0340 mistake is replacing the cam sensor two or three times when the real fault is oil in the connector, a broken wire, or cam timing that has shifted. If a good-quality sensor does not cure it, stop buying sensors and test the circuit and the timing.

Tools you need for P0340

Digital multimeter - Reference voltage, ground, and signal checks separate a wiring fault from a failed sensor.
OBD2 scanner - Shows companion timing codes and confirms the code stays cleared after the repair.

Parts you may need for P0340

Camshaft position sensor - Match the part to your exact engine and bank. Many come with a new O-ring - use it.
Sensor connector pigtail - An oil-soaked or corroded connector will make even a new sensor read badly.
Dielectric grease - A small amount on the connector seal keeps moisture and corrosion out after the repair.

P0340: DIY or pay a shop?

Difficulty: Easy. Time: 0.3 - 1.5 hours. DIY parts: $20 - $120. Shop total: $120 - $400.

Most camshaft position sensors are held by one bolt on top of or at the front of the engine, and replacing one is among the simpler sensor jobs. It becomes a shop job only when the code survives a new sensor and the timing belt or chain needs checking - that is not a driveway diagnosis for most owners.

How to stop P0340 coming back

Change oil on schedule and replace the timing belt on time. Clean oil keeps timing chains and tensioners healthy, and a timing belt replaced on its interval cannot jump a tooth. Both protect the cam timing that the camshaft position sensor reports on. ServiceSage tracks oil changes and the timing belt interval for your vehicle and reminds you before either is due. Track this maintenance free.