Powertrain, shared range

P3489 Cylinder 12 Deactivation/Intake Valve Control Circuit/Open

Check engine lightOn

EmissionsRelevant

Drive cycleNot required

Limp modeNo

P3489 reports that the circuit to the actuator for deactivation or the intake valve of cylinder 12, the highest cylinder number in this code series, is open. No manufacturer documents this code publicly; J2012 reserves the codes for cylinders 9 to 12 for engines with more than eight cylinders. Twelve-cylinder engines with shut-off span Mercedes' late-1990s V12, which deactivated every second cylinder in the firing order, Lamborghini's Aventador V12 that shuts down one cylinder bank below 135 km/h, and Bentley's W12. The Mercedes engine used a hydraulic solenoid pack, the kind of part such a circuit would drive; the bank-based systems publish no equivalent. Comparable logic on GM V8s calls a circuit open above 200 kohm with the output idle. P3491 and P3492 report shorts, P3490 a functional fault, P3493 the exhaust valve.

Likely causes

Wire to the cylinder 12 actuator open or chafed

Cylinder 12 actuator coil open

Loose or corroded connector at cylinder 12

Output stage of the control module failed

Symptoms

Check engine lamp on
Engine no longer runs in reduced-cylinder mode
Somewhat higher fuel use on the highway

Repair estimate

DifficultyMediumDIY possible

Parts and labour€60–900

Time0.5–4 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

cylinder deactivation solenoidwiring harnessecm

References: law.cornell.edu, en.wikipedia.org, newatlas.com, gsi.ext.gm.com.