P3425Cylinder Deactivation (AFM/DoD)

Cylinder 2 Deactivation/Intake Valve Control Performance

P3425 indicates a performance or stuck condition in the cylinder 2 deactivation / intake valve control system on GM AFM/DoD V8s. The lifter is not switching states as commanded.

🚗 Yes in many cases, but address before a stuck lifter causes damage.

MEDIUM

severity

🎯 Top Causes, Ranked by Likelihood

#1Stuck cylinder 2 AFM lifter$1200-$2500

40%

The classic GM AFM lifter failure on cylinder 2.

#2Low or inconsistent oil pressure$50-$400

25%

AFM needs stable oil pressure to actuate lifters.

#3Lifter oil manifold solenoid stuck$300-$700

25%

The solenoid does not flow oil correctly to cylinder 2.

#4Wrong or dirty oil$50-$150

10%

Incorrect oil affects AFM operation.

🩺 Common Symptoms

Check engine light
Lifter tick
Misfire on cylinder 2
Rough running
Reduced power

💰 Repair Cost: DIY vs Shop

DIY Cost

$100-$1500

Shop Cost

$300-$2500

📋 Free OBD2 Code Cheat Sheet

The 50 most common codes with likely cause and DIY fix cost. Sent once, no spam.

🔧 How to Diagnose P3425

1Check oil level, condition, and pressure

2Command AFM on/off with a scan tool

3Inspect the cylinder 2 solenoid and lifter

4Replace the lifter or delete AFM

❓ Frequently Asked Questions

What causes P3425?

Usually a stuck cylinder 2 AFM lifter or a solenoid that will not flow oil, often with low oil pressure.

Can I drive with P3425?

Short term yes, but a stuck lifter can damage the cam or pushrod. Fix it if you hear ticking.

Is P3425 common on GM?

Yes, it is a well-known Active Fuel Management issue on 5.3L and 6.2L V8s.

🔗 Related Codes

P3400P3421P3441P0302