P0340Camshaft Position Sensor A Circuit Bank 1 or Single Sensor
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- The camshaft position sensor, almost always a Hall sensor, tells the engine module which stroke cylinder 1 is in – one crank revolution alone is ambiguous – and measures the actual cam phase with variable timing. Sensor A is the intake camshaft, bank 1 the side with cylinder 1. P0340 means no or too few cam pulses arrive while the crankshaft turns in sync. GM sets it after 5.5 s (or 4 s) of cranking without a cam pulse or fewer than 4 pulses in 3 s running, petrol engines after two trips. Ford checks the ratio of cam to crank events from 200 rpm. The engine usually keeps running but starts longer and loses power as cam timing is held. Bulletins: corroded connectors on GM V8s (PIP5335C), moisture in the oil on short trips in Ford hybrids (SSM 48598).
- What you may notice
- Check engine light on
- Longer cranking before the engine starts
- Loss of power (cam timing held in its base position)
- Rough idle, occasionally stalling
- Likely causes
- LikelyCamshaft position sensor faulty (heat, moisture)
- LikelyConnector or wiring corroded or open, 5 V reference disturbed
- PossibleTone wheel on the camshaft or phaser damaged, loose or at the wrong distance
- PossibleTiming drive jumped or wrongly assembled
- RareMoisture in the engine oil from short trips (Ford hybrids)
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Easy · Often possible to do yourself.Typical cost: €40 – €300
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.