Powertrain, shared range

P3401 Cylinder 1 Deactivation/Intake Valve Control Circuit/Open

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P3401 points to a broken control path to the solenoid that switches off cylinder 1, a cylinder that GM and Chrysler V8s and Ford's 1.5 l three-cylinder EcoBoost all deactivate. On the 2019 L84 and L86 V8s, GM looks at the low-side output while it is off: over 200 kilohm to ground counts as open, and 20 failures among 25 readings at 250 ms intervals make it a Type B fault. GM adds that some controllers store P3403 alongside. Ford's VDE monitor relies on the fault status of its smart driver and decides within 5 seconds. For the 5.7 l Hemi, a Chrysler STAR case describes a deformed manifold heat shield that rubs the MDS solenoid harness open. P3403 and P3404 cover shorts, P3402 the mechanical function. Deactivation is then locked out.

Likely causes

Control wire broken or worn through, e.g. by a hot exhaust heat shield
Loose, corroded or oil-soaked solenoid connector
Open coil in the cylinder 1 deactivation solenoid
Faulty output stage in the engine control module

Symptoms

  • Check engine lamp on, on GM after the second trip
  • Engine stays in all-cylinder mode
  • Slightly higher fuel consumption

Repair estimate

DifficultyMediumDIY possible
Parts and labour€60–900
Time0.5–4 h

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

Parts involved

cylinder deactivation solenoidwiring harnessecm

Related codes

P3402P3403P3404P3405P3400P3498

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