Powertrain, shared range

P3439 Cylinder 5 Exhaust Valve Control Circuit Low

Check engine lightOn

EmissionsRelevant

Drive cycleNot required

Limp modeNo

P3439 would report a short to ground in the control circuit of a dedicated exhaust valve actuator on cylinder 5. No manufacturer documents this code publicly, and no threshold is published for it. The closest documented reference is the intake-side P3435, which GM's L84 sets at under 0.5 ohm to ground with the driver off, after 20 of 25 samples. CARB's output component rules call for exactly this kind of short-circuit check on any actuator that can affect emissions. Engines that switch both valves of cylinder 5 with one solenoid report a short only through P3435. Exhaust-side siblings are P3437 (open), P3438 (function) and P3440 (short to power).

Likely causes

Control wire of the exhaust actuator grounded

Internally shorted exhaust actuator

Faulty engine control module output

Symptoms

Check engine lamp on
Engine runs on all cylinders only

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

P3437 P3438 P3440 P3435 P3400

References: law.cornell.edu, gsi.ext.gm.com.