P3440: Cylinder 5 Exhaust Valve Control Circuit High

P3440 closes the cylinder 5 block and stands for a high signal, usually a short to supply voltage, in the circuit of a separate exhaust valve actuator. No manufacturer documents this code publicly. The code only makes sense on an engine with a separate exhaust actuator; a Ford patent, for example, checks via exhaust pressure whether an exhaust valve still opens after deactivation. Current production systems that deactivate cylinder 5 drive both valves from one solenoid, and GM reports a short to power there as P3436, checked with the driver on and a 0.5 ohm limit. If a dedicated exhaust channel did short high, the computer would stop using deactivation and light the lamp. Compare P3437, P3438 and P3439.

Medium severity. Can I keep driving?Drive little and gently. If you hear timing chain noise or the oil light comes on, shut off the engine.

Cylinder 5 is numbered according to the manufacturer: check your engine's manual before working on it.

Symptoms

Check engine lamp on
Cylinder deactivation unavailable

Most likely causes

Exhaust actuator control wire shorted to voltage
Shorted actuator coil
Engine control module output stage fault

What to check, in order

Start with the simplest. You can tick off each step.

Check the oil level and condition before anything else
Check the sensor's ground and make sure the signal wire is not receiving voltage from another circuit.
Check the solenoid valve's connector
Compare commanded and actual angles in live data
Test the solenoid valve and its filter, if it has one
Check the engine timing if there is chain noise

Good to know

Repair difficulty: medium
It affects emissions.

What each character of P3440 means

P: Powertrain: engine and transmission
3: Generic or manufacturer code, depending on the range
4: Emissions
40: Specific fault in that system

Frequently asked questions

Can I keep driving with code P3440?

Drive little and gently. If you hear timing chain noise or the oil light comes on, shut off the engine.

What causes code P3440?

The most common causes are: exhaust actuator control wire shorted to voltage; shorted actuator coil; engine control module output stage fault.

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.