P0340 code: Camshaft Position Sensor A Circuit Malfunction (Bank 1)
P0340 means camshaft Position Sensor A Circuit Malfunction (Bank 1). The code says where to look, not what failed — the fix depends on which cause your car actually has.
What P0340 means
The camshaft position sensor tells the computer where the valves are in their cycle, which it uses (together with the crank sensor) to time fuel injection and spark precisely. P0340 means that camshaft signal is missing or erratic. Usually it's a failed sensor or a wiring/connector fault, but it can also reflect a real timing problem — a jumped or stretched timing chain/belt. A bad cam signal can cause hard starting, stalling, or a no-start, so it's worth sorting out promptly.
P0340 symptoms
- Hard starting or extended cranking
- Stalling or rough running
- Hesitation and reduced power
- Occasional no-start
- Check-engine light
What it costs to fix P0340
Typical range: $120–$500 · about ~0.3–2.5 hrs of labor
| If the cause is… | Part | Labor |
|---|---|---|
| Camshaft position sensor | $30–$200 | ~0.3–2 hrs |
| Wiring / connector repair | $10–$120 | ~0.5–1.5 hrs |
The sensor is usually a low-hundreds job; labor depends on access. A genuine timing-chain or belt problem is a major repair that varies far too much to quote — get it diagnosed if the sensor and wiring check out.
The price swings on which cause it turns out to be — so confirm the cause before paying. Diagnose P0340 for my exact vehicle →
How to fix P0340
Easy — basic tools, most owners can do this
- Check the cam sensor connector
The camshaft position sensor usually sits on top or at the front of the cylinder head, making it one of the easier sensors to reach. Unplug it, inspect for oil in the connector (a common issue when a valve-cover seal weeps), clean it, and reseat it firmly.
- Replace the camshaft position sensor
On most engines this is one bolt and an O-ring — smear a little clean engine oil on the new O-ring, seat the sensor, and torque the bolt snugly. A failed sensor is the most common cause of P0340, and the part cost is modest.
- Inspect the harness near the valve cover
The sensor's wiring runs close to a hot valve cover and can chafe or harden over the years. Check the visible run for melted, cracked, or rubbed-through insulation and repair any damage properly.
- Verify engine timing if the code returns
A P0340 that comes back with a new sensor and good wiring can mean the timing chain or belt has jumped or stretched, putting the cam out of position relative to the crank. Checking cam/crank correlation is shop-level diagnosis — don't ignore it, because a failing chain can escalate to engine damage.
DIY or shop? This is one of the friendlier sensor codes for DIY: the sensor is usually accessible, cheap, and held by a single bolt, so most owners can do the connector check and replacement in under an hour. The shop threshold is a code that survives the new sensor — cam/crank correlation and timing-chain evaluation require tools and expertise beyond driveway work. Keep in mind the car may stall or fail to start while this fault is active, so plan diagnosis at home rather than driving it around.
Tools for the DIY steps: OBD-II scanner · Socket set · Clean engine oil (for the O-ring) · Electrical contact cleaner
Not sure which step applies to your car? Get the likely cause for your exact vehicle before buying anything for P0340.
Start a case with P0340 and your car. Redline weighs these causes against what your car shows, and names the check that would settle it before you buy parts.
Can I drive with P0340?
Redline can’t determine from a symptom or code alone whether your car is safe to drive.
P0340 on specific vehicles
The likely causes shift by model. We’ve written up the patterns we see most:
P0340: common questions
Can I drive with P0340?
Whether it should be driven can't be read from the code alone. It can cause stalling or a no-start, so get it diagnosed promptly and don't rely on the car for important journeys. If the cause turns out to be timing-related, stop driving and have it checked.
Will P0340 cause a no-start?
It can. Many engines can still start using the crank sensor alone, but a missing cam signal often causes hard starting, long cranking, or stalling — and on some engines, a no-start.
Is P0340 the sensor or the timing chain?
Most often it's the sensor or its wiring, which is the cheaper fix. But it can also flag a jumped/stretched timing chain or belt — a serious repair — so it's worth confirming before assuming it's just a sensor.
How much does it cost to fix P0340?
The sensor is typically a low-hundreds repair depending on access. A timing-chain or belt repair is a major job and much more expensive, which is why diagnosis matters before buying parts.
Symptoms that trigger P0340
Drivers who get this code often notice one of these. Each has its own causes and cost guide:
Related trouble codes
Don’t have a scanner yet? A ~$25 Bluetooth adapter reads codes like P0340 from your phone. See our guide to the best OBD2 Bluetooth adapters. Run a repair shop? See Redline for shops.
Generic OBD-II reference. Manufacturer-specific behavior varies. Confirm with a scan tool and, for safety-related codes, a professional inspection. Cost ranges are reference ranges, not quotes.
Seeing P0340 on your car?
Every problem becomes a Case. Tell Redline what the car is doing: it shows what the evidence supports, what’s still missing, and what to check next, before you approve a repair.
“Inner pad ~1 mm. Outer pad 3 mm.”
Next: check the slide pins move freely before buying parts.