P3402Cylinder Deactivation (AFM/DoD)

Cylinder 1 Deactivation/Intake Valve Control Performance

P3402 indicates a performance or stuck condition in the cylinder 1 deactivation / intake valve control system. The lifter is not deactivating or reactivating as commanded, often due to oil pressure or a mechanically stuck AFM lifter.

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

MEDIUM

severity

🎯 Top Causes, Ranked by Likelihood

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

40%

The lifter fails to switch states, the classic GM AFM failure.

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

25%

AFM needs stable oil pressure; low pressure prevents lifter actuation.

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

25%

The solenoid does not flow oil correctly to cylinder 1.

#4Wrong oil viscosity or dirty oil$50-$150

10%

Incorrect oil affects AFM lifter operation.

🩺 Common Symptoms

Check engine light
Lifter tick
Misfire on cylinder 1
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 P3402

1Verify oil level, condition, and pressure

2Command AFM on/off with a scan tool and watch response

3Inspect the cylinder 1 solenoid and lifter

4Replace the failed lifter or delete AFM

❓ Frequently Asked Questions

What causes P3402?

Most often a stuck cylinder 1 AFM lifter or a solenoid that will not flow oil correctly, aggravated by low oil pressure.

Can I keep driving with P3402?

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

Does an oil change help P3402?

Correct viscosity clean oil can help if the cause is oil related, but a mechanically stuck lifter needs replacement.

🔗 Related Codes

P3400P3401P3425P0301