Camshaft Position Sensor A Circuit Malfunction (Bank 1)
Engine · Timing
The camshaft position sensor is not sending a valid signal. Critical for fuel injection timing. Engine may stall or not start.
- Failed camshaft position sensorMost common
- Damaged reluctor ringCommon
- Timing chain jumpedLess common
Vehicles most commonly affected by P0340
Camshaft position sensor failures are most common on Nissan and Infiniti vehicles with VQ-series V6 engines (CMP sensor failure is the single most common check engine code on these engines), Hyundai and Kia 2.0L and 2.4L engines, and Honda Accord with J-series V6 engines. Timing chain-equipped engines often show P0340 as an early warning sign of timing chain stretch.
Real-world P0340 diagnosis scenario
A 2007 Nissan Altima 3.5L V6 with 88,000 miles intermittently fails to start — cranks for several seconds before catching. P0340 is stored. The CMP sensor on the VQ35DE engine is located on the valve cover and exposed to engine heat. The sensor fails intermittently when hot. Replacing the CMP sensor ($35–$80 for the part) is a 15-minute DIY repair on this engine and resolves the intermittent no-start condition immediately.
On Nissan VQ-series engines, if P0340 is stored along with a rough idle that improves after 60 seconds of warm-up, check the CMP sensor wiring harness for chafing against the valve cover — a known issue on 2003–2008 Altima and Maxima models.
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Frequently asked questions about P0340
What does P0340 mean?
The camshaft position sensor is not sending a valid signal. Critical for fuel injection timing. Engine may stall or not start.
Is P0340 serious?
Car may not start — fix immediately.
How much does it cost to fix P0340?
Repair costs for P0340 range from $100 – $300 depending on the root cause and your vehicle.
Can I drive with P0340?
No — this code indicates a serious issue. Stop driving and have the vehicle inspected immediately.
Can I drive with P0340?
With caution and only short distances. The engine may start and run normally, or may experience hard starts and stalling. P0340 indicates the PCM cannot reliably read camshaft position — avoid highway driving and fix within 24–48 hours.
Could P0340 be caused by a timing chain issue?
Yes. A stretched timing chain causes the camshaft to be out of phase with where the crankshaft expects it to be, which the PCM reads as an invalid cam signal. If P0340 appears alongside P0016 (crankshaft/camshaft correlation), inspect the timing chain for stretch.
How do I find the camshaft position sensor on my vehicle?
The CMP sensor is typically located near the top of the engine on or near the valve cover, or at the front of the engine near the timing cover. It has a 2 or 3-pin electrical connector. Your vehicle's service manual or a quick search for your year/make/model will show the exact location.