Fix P3400: Mechanic’s solutions that WORKED

The code P3400: Cylinder Deactivation System Bank 1 points out a fault in the cylinder deactivation system of Bank 1, and it is most likely caused by issues with deactivation solenoids, low oil pressure, or problems in the lifter oil manifold.

P3400 quick overview

Description	P3400: Cylinder Deactivation System Bank 1
Is it serious?	This code is serious as it affects engine performance and efficiency.
Possible causes	– Faulty cylinder deactivation solenoids – Low engine oil pressure – Problems with the lifter oil manifold – Sludge build-up affecting lifters
How to diagnose?	Check Oil Level and Pressure: Verify the engine oil level and pressure are within specifications. Inspect Solenoids: Evaluate the condition and operation of the cylinder deactivation solenoids. Examine Lifter Oil Manifold: Inspect the lifter oil manifold for any signs of damage or blockage. Look for Sludge: Check for sludge build-up that may be affecting the lifters.

How to fix P3400 – learn from mechanics

I looked into P3400 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.

Case #1: Honda

Vehicle Information: 2013 Honda Pilot EX-L 3.5L

Issue + Repair History:

• MIL on with code P3400.
• Road test showed specific solenoids and pressure switches activating while others did not.
• No misfires detected.

Suggestions to Fix Issue:

• Check TSB 13-055 for issues related to this model and code.
• Inspect and possibly replace the rocker arm oil pressure switch.
• Consider replacing the solenoid pack that comes with the switch.

Final Fix:

• Replaced the rocker arm oil pressure switch.
• After about a week, no recurrence of the issue, thus considering it resolved.

Case #2: GMC

Vehicle Information: 2010 GMC Yukon Denali 6.2L

Issue + Repair History:

• MIL on with code P3400 (Cylinder deactivate).
• Testing revealed two VLOM solenoids did not sound the same as the other two.

Suggestions to Fix Issue:

• Replace the solenoid plate.
• Consider electrical issues in the VLOM or wiring to the ECM.

Final Fix:

• Removed intake manifold and replaced the VLOM assembly.
• Part used: VLOM assembly, part# 12571609, cost $331.00.

Case #3: Chevrolet

Vehicle Information: 2007 Chevrolet Monte Carlo SS 5.3L

Issue + Repair History:

• Code P3400 for cylinder deactivation system.
• Replaced seized lifter on cylinder #1, but MIL still on.
• Found another lifter on cylinder 1 shooting oil out.

Suggestions to Fix Issue:

• Replace all Active Fuel Management (AFM) lifters.
• Check and possibly replace the lifter manifold.

Final Fix:

• Replaced all AFM lifters.
• Replaced the lifter manifold, resolving the issue.

Case #4: Chrysler

Vehicle Information: 2007 Chrysler 300 C 5.7L

Issue + Repair History:

• Initially had code P3425 and low oil pressure issues.
• Replaced all deactivation solenoids, oil pressure sender, and checked alternator.
• New code P3400 emerged after repairs.

Suggestions to Fix Issue:

• Check lifters for proper functioning.
• Inspect wiring harness for damages or shorts.
• Consider using OEM parts instead of aftermarket.
• Verify engine oil pressure directly with a pressure gauge.

Final Fix:

• Replaced the ECM with a rebuilt unit, which resolved the issue.

Case #5: Cadillac

Vehicle Information: 2010 Cadillac Escalade 6.2L

Issue + Repair History:

• Engine noise and codes P0300, P3400; misfires at cylinders #6 and #7.
• Replaced #6 intake & exhaust lifters, then experienced new issues with MDS solenoids.

Suggestions to Fix Issue:

• Replace the camshaft and lifters.
• Consider replacing the VLOM (Variable Lift and Oil Management) as advised by the dealer.
• Some suggested engine replacement due to high mileage and potential for ongoing issues.

Final Fix:

• Replaced the camshaft, all lifters, cam bolt/actuator, and new VLOM.
• Pulled the motor for camshaft replacement, improving service ease.
• After reinstallation, the truck ran well without noise.

Advice	Diagnostic Step Description
Check for Lifter Functionality	Inspect the lifters, particularly AFM (Active Fuel Management) lifters, for proper operation.
Inspect MDS Solenoids	Evaluate the Multi-Displacement System (MDS) solenoids for any failures or inconsistencies.
Verify Oil Pressure	Ensure that the engine oil pressure is within the manufacturer’s specified range.
Consider Engine Replacement	In cases of high mileage or severe engine damage, engine replacement might be a more viable option.
Check Wiring Harness and Connectors	Examine the wiring harness and connectors for any signs of damage, wear, or improper connections.
Replace Oil Pressure Sender (if applicable)	If there are signs of oil pressure issues, consider replacing the oil pressure sender.