Powertrain, generic · Ignition system or misfire

P0340 Camshaft Position Sensor A Circuit Bank 1 or Single Sensor

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

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).

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)

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

Repair estimate

DifficultyEasyDIY possible
Parts and labour€40–300
Time0.3–2 h

Typical range across vehicles; the real cost depends on what the testing finds.

What to check first

  1. Inspect connector
  2. Check signal while cranking
  3. Verify timing if the sensor is good

Parts involved

camshaft position sensorcamshaft tone wheelsensor wiringengine control moduletiming chain

Related codes

P0341P0344P0345P0365P0016P0335

References: gsi.ext.gm.com, gsi.ext.gm.com, gsi.ext.gm.com, newtonnet.co.uk.