Fix P0354: Mechanic’s solutions that WORKED

The code P0354: Ignition Coil ‘D’ Primary/Secondary Circuit Malfunction indicates a malfunction in the primary or secondary circuit of the ignition coil ‘D’. This issue can arise from various causes, including a faulty coil, wiring issues, or problems with the PCM. It’s essential to diagnose and address this fault to maintain optimal engine performance and prevent potential damage.

P0354 quick overview

Meaning	P0354: Ignition Coil ‘D’ Primary/Secondary Circuit Malfunction
Is it serious?	This code can be serious as it often leads to engine misfires, affecting vehicle performance and fuel efficiency.
Possible causes	– Faulty ignition coil on cylinder ‘D’ – Damaged or faulty wiring to the ignition coil – Poor electrical connections in the coil circuit – Potential issues with the Powertrain Control Module (PCM) – Grounding or short circuit problems in the coil circuit
How to diagnose?	Inspect Wiring and Connectors: Check for damaged, loose, or corroded connections in the coil circuit. Swap Coils: Exchange the suspect coil with another cylinder to see if the fault code changes. Check Coil Power Feed: Ensure consistent and correct power supply to the coil. Wiggle Test on Wires: Manipulate wiring to detect intermittent faults. Use a Scope: Analyze electrical signals from PCM to the coil. Consider PCM Issues: Evaluate if the PCM is malfunctioning. Check for Grounding/Shorts: Look for grounding or short circuits in the wiring.

How to fix P0354 – learn from mechanics

I looked into P0354 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: Ford

Vehicle Information: 1998 Ford F-150 Lariat 4.6L Poor Idle Quality, MIL Lamp on

Issue + Repair History:

• Initially replaced ignition wires and plugs.
• Vehicle stopped, blown fuse encountered.
• Codes 302 & 308 initially present but no longer.
• Persistent issue with code P0354.

Suggestions to Fix Issue:

1. Check for common bad coils issue, possibility of updated coil from Ford.
2. Substitute coil with another to diagnose if the issue is with the coil or elsewhere.
3. Inspect the wiring or control unit if the fault is not in the coil.
4. Check wires at the black square connector next to the battery for burns or breaks.
5. Look for a short in the B+ wire going to the coil.
6. Check for coolant leakage on the number 4 coil from the heater hose and replace the coil, plug, and hose clamp.

Final Fix: Replaced the ignition coil, which corrected the problem.

Case #2: Chrysler

Vehicle Information: 2002 Chrysler Sebring LXi 2.7L Misfire

Issue + Repair History:

• Initially, code P1391 (intermittent loss of cam or crank sensor) detected.
• Replaced pigtail on the cam sensor after a wiggle test showed it was intermittent.
• Experienced bucking during a test drive; misfire counters showed no issues.
• Later, codes P0356 and P0354 (#6 & #4 coil circuits) appeared.
• Checked wiring harness and PCM; replaced PCM with a remanufactured one after freezing test.
• Issue persisted with the same codes after a long test drive.
• Previously, the vehicle had a new (used) engine with 25k and changed coils and plugs.

Suggestions to Fix Issue:

1. Swap coils with another cylinder to check if the misfire changes with the coil.
2. Inspect coil circuit from PCM.
3. Scope secondary system on the coil.
4. Open harness and check splices; conduct load test on wires.
5. Look for corroded or chaffed wiring on the driver’s side of the engine above the transmission.
6. Move coils to other cylinders to see if codes follow the coils.

Final Fix: The issue was resolved with the replacement of the OEM crank sensor.

Case #3: Jaguar

Vehicle Information: 2005 Jaguar S-Type Sport 4.2L Misfire

Issue + Repair History:

• Customer initially replaced ignition coils on cylinders #5 and #6 as diagnosed by Jaguar, but misfire persisted.
• After diagnostic approval, codes P0354 and P0304 were found.
• Swapped coil and spark plug of cylinder #4 with known good ones, but issue remained.
• Compression test showed 160psi across the board.
• Noid light test revealed #4 injector firing only at vehicle start, then shutting off within 5 seconds.
• Initial wiggle test on coil connector wires did not reveal any issues.

Suggestions to Fix Issue:

1. Current ramp (scope) the number 4 primary circuit and compare with others to identify any issues.
2. Verify that the misfiring cylinder is indeed cylinder #4.
3. Unplug the coil while running to determine the actual misfiring cylinder.
4. Check wiring to the computer for any faults.

Final Fix:

• After much frustration, a more forceful pull on the coil connector wires resolved the misfire.
• This action was taken following an initial, less forceful wiggle test that did not reveal the problem.

Case #4: Toyota

Vehicle Information: 2003 Toyota Camry SE 2.4L Misfire, MIL Lamp on

Issue + Repair History:

• Initial issue with cylinder #1 misfire and codes P0351 through P0354.
• Diagnosis of ignition coil circuit codes found no apparent problem.
• Misfire occurring only at cold start.
• Plugs were new, coils, and wiring visually intact.
• Cleared codes, but car returned after a week with cylinder #1 misfire and P0351.
• Questioned if the issue could be resolved by reflashing or if something was overlooked.

Suggestions to Fix Issue:

1. Check the brand of the spark plug and if there is any remote start or alarm connected to the ignition circuit or injectors.
2. Swap coil pack of cylinder #1 with another to see if the misfire moves.
3. Check the IGF wire from the coil to the ECU terminal for connection issues and ensure the female terminal friction is adequate.

Final Fix:

• Replaced the injector in cylinder #1.
• The vehicle has not coded anything for several weeks, suggesting a resolution.
• The connection between the bad injector and the IGF signal codes on all 4 cylinders remained unclear, leading to the assumption that a bad connector was inadvertently fixed during testing.

Case #5: Chevrolet

Vehicle Information: 2007 Chevrolet Express 3500 6.0L Misfire

Issue + Repair History:

• Came in with a P0354 code and a misfire on cylinder 4.
• Initially replaced the coil with a new Delphi coil; cleared code and test drove with no issues.
• Two weeks later, the same code and misfire reappeared.
• Replaced the coil again, but the problem persisted.
• Tested coil and wiring without conclusive results; suspected PCM but not certain.

Suggestions to Fix Issue:

1. Consider replacing the coil connector and checking the coil ignition power feed wire.
2. Inspect all wiring and connectors to the cylinder; check resistance of fuel injectors.
3. Examine related circuit integrity, especially near connectors, and check all PCM B+ and grounds.
4. Look for bad wiring, potentially requiring new wires from PCM to coils and injectors.
5. Check for bad ground from engine to frame.
6. Investigate potential severely corroded PCM.
7. Use a scope to observe the signal from PCM and power supply to coil.

Final Fix:

• Found that the common wire for cylinder 4 was rubbed through and grounding out, after inspecting the wire harness tucked under the fuel rail.
• Fixed the wire and relocated the harness, resolving the issue.

Advice	Brief Description of Diagnostic Step
Inspect wiring and connectors	Check for any visible damage, corrosion, or loose connections.
Swap the coil with another cylinder	Determine if the misfire or code follows the coil to a new location.
Check coil ignition power feed	Verify the power supply to the coil is consistent and correct.
Perform a wiggle test on wires	Manipulate wiring to see if the issue is temporarily resolved or worsened.
Use a scope to observe signals	Analyze the electrical signal from PCM to the coil for irregularities.
Consider potential PCM issues	Evaluate if the Powertrain Control Module could be the source of the problem.
Check for grounding or short issues	Look for any wires that might be grounding out or have short circuits.