Powertrain, shared range

P3495 Cylinder 12 Exhaust Valve Control Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P3495 points to a low signal, usually a short to ground, on the control line of the cylinder 12 exhaust valve actuator. No manufacturer documents this code publicly; J2012 reserves the codes for cylinders 9 to 12 for engines with more than eight cylinders. The twelve-cylinder engines with deactivation (Bentley W12, Lamborghini Aventador V12, Mercedes M137) are not documented with a dedicated exhaust actuator per cylinder; the newer ones shut entire banks and keep the valves moving, as Bentley states for its W12. Where such an actuator does exist, the diagnosis follows the usual path: connector unplugged, resistance of the wire to ground, then the coil itself. P3493 is the open circuit, P3496 the short to voltage, and P3491 the low fault on the intake side of cylinder 12.

Likely causes

Exhaust actuator wire of cylinder 12 grounded
Exhaust actuator with internal short
Control module output faulty

Symptoms

  • Check engine lamp on
  • Cylinder deactivation inactive

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

Related codes

P3493P3494P3496P3491P3497

References: law.cornell.edu, mobilityengineeringtech.com, bentleymedia.com, en.wikipedia.org.