P3426Cylinder 4 Deactivation/Intake Valve Control Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- P3426 is one of the few performance codes in this range that makers really use. FCA calls it Cylinder 4 Deactivation Control Performance on the 6.4 l Heavy Duty Hemi with MDS; bulletins 18-082-16 and 18-036-20 list it with P3402, P3442 and P3450 and fix it with new PCM software. Ford stores it on the 2025 F-150 5.0 l: bulletin 25-2487, replaced by 26-2093, traces P3402 and P3426 to a restricted oil feed tube for the right-bank deactivation solenoids, which is replaced under the valve cover. GM checks cylinder 4 mechanically under P349B instead. Circuit faults are P3425, P3427 and P3428. The lamp comes on, and the engine may run rough or stay in full-cylinder mode.
- What you may notice
- Check engine lamp on
- Misfire on cylinder 4 or rough running
- Drone or shudder at light throttle
- Likely causes
- LikelyRestricted oil feed tube to the deactivation solenoids (Ford 5.0 l, TSB 26-2093)
- PossibleControl software needing an update (FCA 6.4 l Hemi)
- PossibleLow or worn-out engine oil
- RareDeactivating lifter of cylinder 4 sticking
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €100 – €3,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.