P3493Cylinder 12 Exhaust Valve Control Circuit/Open
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P3493 applies to a separately controlled exhaust valve on cylinder 12 and reports that its actuator circuit is open. No manufacturer documents this code publicly; J2012 reserves the codes for cylinders 9 to 12 for engines with more than eight cylinders. Bentley's W12 and the Lamborghini Aventador V12 shut off banks; Bentley explicitly keeps the valves operating, and Lamborghini describes only the switch to six cylinders below 135 km/h. A GM patent treats the exhaust valves as a step of their own, stopping them before the intake valves, while GM's later production design drives both valves of a cylinder from one solenoid. An open exhaust circuit on cylinder 12 therefore points to a rare design. P3495 and P3496 are the short-circuit codes, P3494 the function, P3489 the intake side.
- What you may notice
- Check engine lamp on
- Partial-cylinder operation unavailable
- Likely causes
- PossibleWire to the cylinder 12 exhaust actuator open
- PossibleCoil of the cylinder 12 exhaust actuator interrupted
- PossibleExhaust actuator connector corroded
- RareControl module output failed
- 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.