Fix P2311: Mechanic’s solutions that WORKED

The OBD2 code P2311 indicates a problem with the secondary circuit of Ignition Coil “D.” This code suggests that the coil’s electrical pathway, which helps spark the fuel-air mixture in the engine, has an issue that could lead to inefficient engine performance. Such a problem can manifest as misfires, reduced fuel efficiency, and potentially rough idling, making it important for vehicle owners to address promptly.

P2311 quick overview

Meaning	P2311: Ignition Coil D Secondary Circuit
Is it serious?	Yes, it can lead to engine misfires, poor performance, and increased emissions.
Possible causes	– Faulty ignition coil – Poor electrical connection in ignition coil circuit – Use of non-OEM spark plugs – Damaged coil wiring harness or connectors – Faulty engine control module (PCM)
How to diagnose?	Inspect the ignition coil and wiring for damage or wear. Check the spark plugs to ensure they meet OEM specifications. Test electrical connections for the coil, looking for loose or corroded connectors. Perform a compression test to rule out mechanical issues. Consider an injector balance test to assess fuel delivery consistency.

How to fix P2311 – learn from mechanics

I looked into P2311 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: Dodge

Vehicle Information 2014 Dodge Journey SXT 3.6L

Issue + Repair History

• MIL on and misfiring initially
• DTCs: P0302, P0303, P0304, P2311
• Replaced spark plugs with NGK LKR7BHX initially, then reverted to OEM spark plugs
• Replaced all ignition coils
• Intermittent misfire persists despite repeated replacements

Other OBD2 Codes + Test Results

• P2311: Ignition Coil D Secondary Circuit

Mechanic Suggestions

• Advises against using Bosch spark plugs and recommends sticking with OEM Champion spark plugs
• Suggests checking for proper spark plug application based on vehicle specifications
• Recommends inspecting wiring harness for ignition coils and ensuring proper connection
• Proposes performing compression and leak down tests on all cylinders, followed by visual inspection of camshafts and rockers
• Advocates for running a compression test over a static test and suggests an injector balance test

Final Fix

• Discovered loose bulkhead connector containing injector and coil wiring
• Manipulated and cleaned connector, ensured proper locking, and secured with tie strap
• Misfire resolved after connector maintenance

Case #2: Dodge

Vehicle Information 2004 Dodge Ram 1500 SLT 5.7L

Issue + Repair History

• Check engine light on
• Codes: P2320 on #7, P2311 on #4
• Replaced spark plugs, wires, and coils for #4 and #7
• No improvement in performance

Other OBD2 Codes + Test Results

• P2320: Ignition Coil #7 Secondary Circuit Insufficient Ionization
• P2311: Ignition Coil #4 Secondary Circuit Insufficient Ionization

Mechanic Suggestions

• Suggested performing a compression test to check for dropped valve seats or cracked plugs
• Advised checking valve springs for breaks, as intermittent misfires could be caused by broken valve springs
• Recommended inspecting wiring to coils and checking for rodent damage
• Suggested checking engine vacuum and performing basic tests such as compression, leak down, and vacuum tests
• Proposed checking for low compression due to bad valve seats

Final Fix

• Replaced PCM and flashed it
• Misfires resolved after PCM replacement

Case #3: Chrysler

Vehicle Information 2006 Chrysler 300 C 5.7L

Issue + Repair History

• Intermittent misfire on cylinder #4
• Compression tested at 175
• Replaced coils, spark plugs, injector
• Decarbonized engine
• Performed back-to-back oil changes

Other OBD2 Codes + Test Results

• P0304: Cylinder 4 Misfire
• P2311: Ignition Coil D Secondary Circuit

Mechanic Suggestions

• Suggested checking for broken valve springs, especially common in these engines
• Advised using Champion spark plugs for Chrysler engines and checking for lower quality coils
• Recommended performing a leakdown test to check for a possible exhaust valve starting to burn
• Suggested checking for internal vacuum leaks, particularly the intake manifold gasket
• Proposed inspecting the cam and lifter on cylinder #4 for potential issues, as secondary circuit fault can indicate valve problems
• Advised switching coil and plug from cylinder #4 to another cylinder to troubleshoot, as well as considering issues with the valve/spring, head gasket, or electrical system

Final Fix

• Identified lifter on cylinder #4 as the issue, which caused intermittent misfire
• Engine sent to machine shop for repair after confirming diagnosis

Diagnostic Step	Explanation
Inspect the ignition coil and wiring	Look for any signs of damage or wear that could interrupt the coil’s function.
Check the spark plugs	Ensure they are the correct type for your vehicle and in good condition.
Test electrical connections	Examine coil connectors for looseness or corrosion that might impair electrical flow.
Perform a compression test	Rule out underlying mechanical issues that could contribute to misfires.
Consider an injector balance test	Evaluate the consistency of fuel delivery to each cylinder, identifying potential fuel issues.

In the service cases reviewed, P2311 was linked to various causes and fixes, from simple connector cleanups and ensuring the use of OEM spark plugs to more complex solutions like PCM replacement or mechanical repairs to the engine. These examples underscore the importance of thorough diagnostics to identify the root cause of ignition-related misfires and ensure the correct fix, thereby restoring smooth engine operation and preventing further issues.