P34A0Cylinder 9 Deactivation/Intake Valve 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
- P34A0 is reserved for a cylinder 9 that keeps its valves moving after the engine computer has ordered it off, which presumes an engine with at least nine cylinders and per-cylinder valve switching. No manufacturer documents this code publicly. The twelve-cylinder engines with deactivation found so far work bank by bank; Bentley's W12 in the 2020 Bentayga Speed, for example, alternates between two complete banks of six. A monitor would work like GM's tests for cylinders 1 to 8 (P3498 to P349F), where manifold pressure that stays too high in skipped events reveals a cylinder that is still breathing. CARB requires such mechanical checks for valve control systems. P3466 is the control-performance code for cylinder 9.
- What you may notice
- Check engine lamp on
- Rough running in reduced-cylinder mode
- Higher fuel use
- Likely causes
- LikelySwitching lifter or rocker of cylinder 9 stuck
- PossibleOil control valve for the deactivation not switching
- PossibleLow or degraded oil
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €150 – €6,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.