P3401Cylinder 1 Deactivation/Intake Valve Control Circuit/Open
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- 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.
- What you may notice
- Check engine lamp on, on GM after the second trip
- Engine stays in all-cylinder mode
- Slightly higher fuel consumption
- Likely causes
- LikelyControl wire broken or worn through, e.g. by a hot exhaust heat shield
- PossibleLoose, corroded or oil-soaked solenoid connector
- PossibleOpen coil in the cylinder 1 deactivation solenoid
- RareFaulty output stage in the engine control module
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €60 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.