P3423Cylinder 3 Exhaust Valve Control Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P3423 points to a grounded control wire at a dedicated cylinder 3 exhaust actuator. No manufacturer documents this code publicly, and NHTSA's 2025 look at GM's DFM engines shows why: each cylinder has just one lifter oil solenoid, and it feeds both lifters, intake and exhaust, so there is no separate exhaust output that could fail. For that same solenoid on cylinder 3, GM's L84 table flags a resistance to ground under half an ohm at rest and files it as P3419. The 2007 Displacement on Demand application likewise lists only one solenoid circuit for cylinder 3. Any design with its own exhaust output would fall under the CARB duty to detect shorts. Effect: warning lamp, cylinder 3 stays active.
- What you may notice
- Check engine lamp on
- No switch to reduced-cylinder operation
- Likely causes
- PossibleExhaust actuator wire of cylinder 3 shorted to engine ground
- PossibleActuator winding shorted to its housing
- RareFaulty output stage in the 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.