P3448: Cylinder 6 Exhaust Valve Control Circuit High

If cylinder 6 had its own exhaust valve actuator, P3448 would report its control line shorted to battery voltage. No manufacturer documents this code publicly. A GM patent application on cylinder deactivation switches both sides through one shared hydraulic valve and only lets the exhaust valves go first, off and back on, so it shows no separate exhaust control either; GM's production V8s likewise put both lifters on one solenoid and publish only P3444 for a short to power on cylinder 6. That test, below 0.5 ohm to power with the driver switched on and 20 of 25 samples, is the reference for how such a fault would be judged. With the actuator unusable, deactivation is blocked. P3445 to P3447 are the sibling exhaust codes.

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

Symptoms

Check engine lamp on
No switch to reduced-cylinder operation

Most likely causes

Exhaust actuator wire touching a supply line
Shorted turns in the exhaust actuator coil of cylinder 6
Engine control module output stage faulty

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 P3448 means

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

Frequently asked questions

Can I keep driving with code P3448?

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

What causes code P3448?

The most common causes are: exhaust actuator wire touching a supply line; shorted turns in the exhaust actuator coil of cylinder 6; engine control module output stage faulty.

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.