Powertrain, generic (extended)

P2DEC Cylinder 3 Intake Valve Lift Range/Performance

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2DEC applies only to cylinder 3: the lift its intake valves actually achieve is outside the commanded window or arrives too late. Under the CARB rule, a maker must run a failure analysis of any plausible hydraulic or mechanical defect, naming broken return springs, blocked oil passages and a single cylinder's lift pin as examples, and must catch the resulting errors before tailpipe emissions pass the threshold. Two-step valvetrains with fixed states get a relief: they only have to detect faults that actually exceed it. Because a cylinder stuck in the wrong lift fills differently from its neighbours, its combustion becomes unsteady, which is exactly what crank-speed methods like GM's patented one measure. No public manufacturer document names P2DEC; an open or shorted actuator would set a circuit code instead.

Likely causes

Lock pin or switching follower of cylinder 3 not latching
Partly blocked oil passage to the cylinder 3 element
Broken return spring in the lift mechanism

Symptoms

  • Check engine light on
  • Uneven idle, often with a cylinder 3 misfire entry
  • Higher fuel consumption

Repair estimate

DifficultyHardWorkshop job
Parts and labour€150–2,500
Time1–8 h

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

Parts involved

intake valve lift actuator cyl 3vvt system

Related codes

P2DEBP2DEDP2DF0P0303P2CDD

References: law.cornell.edu, image-ppubs.uspto.gov.