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).
Medium severity. Can I keep driving?If the engine starts and runs well, you can drive in moderation to a repair shop, but avoid unnecessary stops and long trips because it may not restart. If it stalls or misfires while driving, do not continue.
Bank 1 is the side of the engine with cylinder 1. Inline engines only have this bank.
Symptoms
- Check engine light on
- Longer cranking before the engine starts
- Loss of power (cam timing held in its base position)
- Rough idle, occasionally stalling
Most likely causes
- Camshaft position sensor faulty (heat, moisture)
- Connector or wiring corroded or open, 5 V reference disturbed
- Tone wheel on the camshaft or phaser damaged, loose or at the wrong distance
- Timing drive jumped or wrongly assembled
- Moisture in the engine oil from short trips (Ford hybrids)
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: easy
- It can trigger limp mode.
- It affects emissions.
What each character of P0340 means
- P: Powertrain: engine and transmission
- 0: Generic code: same on every make
- 3: Ignition and misfires
- 40: Specific fault in that system
Frequently asked questions
Can I keep driving with code P0340?
If the engine starts and runs well, you can drive in moderation to a repair shop, but avoid unnecessary stops and long trips because it may not restart. If it stalls or misfires while driving, do not continue.
What causes code P0340?
The most common causes are: camshaft position sensor faulty (heat, moisture); connector or wiring corroded or open, 5 V reference disturbed; tone wheel on the camshaft or phaser damaged, loose or at the wrong distance.
Related codes
- P0341Camshaft Position Sensor A Circuit Range/Performance Bank 1 or Single Sensor
- P0344Camshaft Position Sensor A Circuit Intermittent Bank 1 or Single Sensor
- P0345Camshaft Position Sensor A Circuit Bank 2
- P0365Camshaft Position Sensor B Circuit Bank 1
- P0016Crankshaft Position - Camshaft Position Correlation (Bank 1 Sensor A)
- P0335Crankshaft Position Sensor A Circuit
Sources
- gsi.ext.gm.com: 18OBDG03A Engine Diagnostics
- gsi.ext.gm.com: 18OBDG04 Engine Diagnostics
- gsi.ext.gm.com: 14OBDG10 Engine Diagnostics
- newtonnet.co.uk: fordobd2012
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.