P3434: Cylinder 5 Deactivation/Intake Valve Control Performance

With P3434 the computer has found that cylinder 5 does not switch off or back on correctly, while the control circuit tests fine. No manufacturer documents this code publicly. GM's L84 runs the equivalent test under P349C: manifold pressure stays too high while cylinder 5 is commanded off, meaning its valves keep working. For 3.6 L V6 engines, GM bulletin 21-NA-036 describes the field picture: misfires on cylinder 5 (P0305), sometimes only after a reduced-cylinder phase, from oil leaking past the control valve or rockers that do not latch, and asks to check for a solenoid tip broken off in the bore. Wiring faults for this cylinder are P3433, P3435 and P3436.

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

Symptoms

• Misfire on cylinder 5 (P0305)
• Check engine lamp on
• Shaking after reduced-cylinder operation

Most likely causes

• Oil leaking past the cylinder 5 control valve seal
• Switching rocker or lifter of cylinder 5 not latching
• Solenoid tip broken off in the bore
• Low or aged engine oil

What to check, in order

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

1. Check the oil level and condition before anything else
2. Compare the reading with other engine data while varying the engine speed.
3. Check the solenoid valve's connector
4. Compare commanded and actual angles in live data
5. Test the solenoid valve and its filter, if it has one
6. Check the engine timing if there is chain noise

Good to know

• Repair difficulty: hard
• It affects emissions.

What each character of P3434 means

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

Frequently asked questions

Can I keep driving with code P3434?

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

What causes code P3434?

The most common causes are: oil leaking past the cylinder 5 control valve seal; switching rocker or lifter of cylinder 5 not latching; solenoid tip broken off in the bore.

Related codes

• P3433Cylinder 5 Deactivation/Intake Valve Control Circuit/Open
• P3435Cylinder 5 Deactivation/Intake Valve Control Circuit Low
• P3436Cylinder 5 Deactivation/Intake Valve Control Circuit High
• P3438Cylinder 5 Exhaust Valve Control Performance
• P349CCylinder 5 Deactivation/Intake Valve Performance
• P0305Cylinder 5 Misfire Detected
• P3400Cylinder Deactivation System Bank 1

Sources

• law.cornell.edu: 13 CCR 1968.2
• gsi.ext.gm.com: 19OBDG03B Diagnostics
• static.nhtsa.gov: MC 10209400 0001

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.