Powertrain, generic · Ignition system or misfire

P03EF A Camshaft Profile Actuator C Control Performance/Stuck Off Bank 1

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

With a sliding camshaft, the intake camshaft (camshaft A) carries movable cam pieces with several lift profiles; solenoid actuators shoot a pin into a groove in the piece and shift it axially. Actuator C is the third of these actuators – not a profile position. The only known user is GM's 2.7-litre turbo four (L3B, three-step sliding cam, from model year 2019). P03EF is the function check: in the standard's wording the actuator does not do what is commanded. A Hall sensor in the actuator reports the pin position. GM uses this code for a pin that extends without being commanded (4 of 5 cylinder events, MIL on the first trip); a pin that does not extend on command shows up there through the cam piece position sensors (GM-specific codes P30BE ff). GM bulletins name swapped actuator connectors and actuators fitted to the wrong camshaft after repairs.

Likely causes

Actuator faulty inside: pin extends uncommanded (weak return spring)
Actuator connectors swapped, or intake and exhaust actuators fitted to the wrong camshaft
Interference in the Hall feedback signal (ground, connector)
Cam piece sticking or shift groove worn

Symptoms

  • Check engine light on
  • Ticking or rattling at the camshaft carrier
  • Misfire, rough idle or less power in the wrong lift profile
  • Lift switching and cylinder deactivation out of service

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€150–1,500
Time0.5–6 h

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

Parts involved

camshaft profile actuator c intakesliding camshaftactuator wiringengine control module

Related codes

P03ECP03F0P03F4P003CP037C

References: gsi.ext.gm.com, patents.google.com, law.cornell.edu, static.nhtsa.gov.