P3403Cylinder 1 Deactivation/Intake Valve Control Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- The engine computer drives the deactivation valve for cylinder 1 through an output stage that checks its own wiring. P3403 means that check found the control line pulled to ground. GM documents it for the L84 and L86 V8s (2019): with the driver off, an impedance below 0.5 ohm to ground counts as a fault, and 20 failures in 25 samples taken every 250 ms set a Type B code, so the lamp comes on after the second trip. Ford's VDE monitor flags the same short via its smart driver within 5 seconds. An open line is P3401, a short to battery voltage P3404, a mechanical failure P3402. The engine then stays in all-cylinder mode, mainly costing fuel.
- What you may notice
- Check engine lamp on after two trips
- Engine no longer switches to reduced-cylinder mode
- Somewhat higher fuel consumption
- Likely causes
- LikelyControl wire chafed against the engine and shorted to ground
- PossibleInternal short in the cylinder 1 deactivation solenoid
- RareOil or water in the solenoid connector
- RareFaulty output driver 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.