P0340 means Camshaft Position Sensor A Circuit (Bank 1 or Single Sensor). The computer is not receiving a usable signal from the camshaft position sensor, which identifies which cylinder is on its compression stroke. It is a generic OBD-II code, so the definition is the same on any make, but the most likely cause varies by engine; confirm with a scan tool and the service information for your vehicle before buying parts.
What P0340 means
The engine computer uses the crankshaft position sensor to know engine speed and piston position, and the camshaft sensors to know which stroke each cylinder is on. On engines with variable valve timing, oil-driven cam phasers rotate the camshafts relative to the crankshaft under the control of solenoids. Timing codes come from a sensor that cannot be read, or from a measured cam angle that does not match the commanded one, so oil level and condition, sensor signals and mechanical timing all need checking.
P0340 symptoms
- Hard starting or long cranking
- Rough running or stalling
- Reduced power on some vehicles
Common causes of P0340
- Failed camshaft position sensor
- Wiring or connector damage
- Damaged camshaft target
- Timing problems on some engines
How to diagnose P0340
- Inspect connector and wiring
- Check the sensor signal with a scope
- Check for related timing codes
Can you drive with P0340?
Often possible but unreliable; hard starts and stalling can strand you. Repair soon.
P0340 tips
Many engines still start without a cam signal by working out the firing order, but cranking takes longer. If the sensor and wiring test good, timing that is off by a tooth, for example after timing chain work, can also set this code.
Will P0340 clear itself?
If the fault stops, the computer turns off the check engine light by itself after several drive cycles without seeing it again, and the code stays in memory as history for a while. Clearing P0340 with a scan tool after a repair is fine, but if the cause is still there the code returns, sometimes within one drive. Disconnecting the battery also clears codes on most vehicles, but it erases learned fuel trims and idle settings as well.
Related codes
| Code | Meaning |
|---|---|
| P0335 | Crankshaft Position Sensor A Circuit |
| P0016 | Crankshaft Position – Camshaft Position Correlation (Bank 1 Sensor A) |
| P0011 | Intake Camshaft Position Timing Over-Advanced or System Performance (Bank 1) |
Guides that help
- camshaft position sensor
- crankshaft and camshaft position sensors
- timing chain and cam phaser symptoms
When it is more than a sensor
If a stretched chain has already jumped time and damaged valves, or low oil pressure has worn the engine, a repair can cost more than a replacement; see engine replacement cost and compare engines by code on our engines page.
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