Powertrain, shared range

P3450 Cylinder 7 Deactivation/Intake Valve Control Performance

Check engine lightOn

EmissionsRelevant

Drive cycleRequired

Limp modeNo

P3450 reports that cylinder 7 does not deactivate or reactivate as commanded while its solenoid circuit checks out. FCA lists it as Cylinder 7 Deactivation Control Performance for the 6.4 l Heavy Duty Hemi with MDS (RAM 2500 to 5500, bulletins 18-082-16 and 18-036-20): the MIL lights and a PCM reflash cures it, with an optional calibration that also eases drone and shudder in MDS mode. On the 2025 F-150 5.0 l, Ford bulletin 26-2093, which replaces 25-2487, pairs it with P3442 and has the left-bank solenoid oil feed tube replaced under the valve cover. In GM's system, as NHTSA describes it, oil pressure moves locking pins so the lifter body travels without opening the valve. GM's L84 uses P349E. Electrical faults: P3449, P3451, P3452.

Likely causes

Restricted oil feed tube to the left-bank solenoids (Ford 5.0 l, TSB 26-2093)

Outdated PCM calibration (FCA 6.4 l, bulletins 18-082-16 and 18-036-20)

Locking pins in a cylinder 7 lifter sticking from wear or dirt

Insufficient or aged oil delaying the switch

Symptoms

Check engine lamp on
Ticking noise from the valve train
Misfire on cylinder 7 (P0307)
Reduced-cylinder mode switched off

Repair estimate

DifficultyHardWorkshop job

Parts and labour€100–3,500

Time0–12 h

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

Parts involved

cylinder deactivation solenoidlifterengine oil

References: law.cornell.edu, static.nhtsa.gov, static.nhtsa.gov, static.nhtsa.gov.