Ignition & misfire · Powertrain · generic (SAE-defined)

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

P0340 means the engine computer detected a problem with the signal circuit for camshaft position (CMP) sensor "A" on bank 1, or the engine's only camshaft sensor.

Severity: Moderate — diagnose within days

Can I drive with P0340? Often yes if the engine starts and runs smoothly, since many engines can run on the crankshaft signal alone. Expect possible hard starting or stalling, and have it diagnosed within a few days.

Standard title per SAE J2012 / ISO 15031-6 · Updated 2026-11-07 · By CarWhere Research

How P0340 sets

The powertrain control module (PCM) uses the camshaft position (CMP) sensor to identify which cylinder is on its compression stroke for sequential fuel injection and, on many engines, to control variable valve timing. P0340 sets when the CMP signal is missing or electrically out of range while the crankshaft signal is present. Conditions are manufacturer-specific.

Common causes of P0340

Roughly most likely first; the actual cause depends on the vehicle and needs testing to confirm.

Failed camshaft position sensor
Open, shorted, or damaged sensor wiring
Corroded or oil-soaked connector
Damaged camshaft reluctor or tone wheel
Timing chain or belt stretched or jumped a tooth
Weak battery or charging voltage affecting sensor signals

P0340 symptoms

Check engine light on
Longer cranking or hard starting
Stalling or rough running
Reduced power or poor fuel economy

How P0340 is diagnosed

Check freeze frame data and look for crankshaft or cam/crank correlation codes.
Inspect the sensor connector and wiring for damage or oil intrusion.
Verify reference voltage, ground, and signal at the sensor connector.
Capture the CMP and crankshaft signals on an oscilloscope to check pattern and alignment.
If a correlation code is present, check timing chain or belt alignment.

Typical fixes for P0340

Replace the camshaft position sensor
Repair wiring or connector damage
Replace leaking seals that allow oil into the connector
Repair timing chain or belt problems if found

Replace parts only after testing confirms the cause — a code names the circuit or condition that failed a check, not necessarily the faulty part. We don’t publish per-repair prices; for what households actually spend on upkeep, see car repair costs.

Manufacturer notes

Definitions of camshaft sensor "A" and "B" vary between manufacturers; some use "A" for intake and "B" for exhaust. Check factory service information.

Related codes & warning lights

P0341P0342P0343P0335 P0016 P0345

Flashing Check Engine Light

P0340 FAQ

What does code P0340 mean?

P0340 means the engine computer detected a problem with the signal circuit for camshaft position (CMP) sensor "A" on bank 1, or the engine's only camshaft sensor. The standard definition is "Camshaft Position Sensor "A" Circuit (Bank 1 or Single Sensor)."

Can I drive with a P0340 code?

Often yes if the engine starts and runs smoothly, since many engines can run on the crankshaft signal alone. Expect possible hard starting or stalling, and have it diagnosed within a few days.

Can the car start with a bad camshaft sensor?

Many engines will still start using the crankshaft signal, though cranking may take longer. Some engines will not start at all without a valid camshaft signal.

Should the timing be checked with P0340?

If a cam/crank correlation code such as P0016 appears alongside P0340, timing chain or belt alignment should be checked before replacing the sensor.

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Engine guides by brand (known issues, specs)

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More ignition & misfire codes

P0300 P0301 P0302 P0303 P0304 P0305 P0306 P0307 P0308 P0320 P0325 P0327

Sources

SAE J2012 — Diagnostic Trouble Code Definitions (standard code titles)
ISO 15031-6 — Road vehicles: communication between vehicle and external equipment for emissions-related diagnostics, Part 6: Diagnostic trouble code definitions
U.S. EPA — Vehicle Emissions Inspection and Maintenance (I/M) programs
U.S. EPA, 40 CFR 86.1806-17 — Federal onboard diagnostics requirements for light-duty vehicles

General information written by CarWhere Research, not a diagnosis of your vehicle. Manufacturers can add their own sub-definitions and test conditions; confirm with the factory service information for your year, make and model. Before paying for a repair, check NHTSA for open recalls and your warranty booklet: federal law requires an emissions warranty on major emission-control parts such as the catalytic converter and engine computer.