The P0351 and P0356 diagnostic trouble codes (DTCs) are common issues in Ford vans, indicating a malfunction in the ignition coil driver circuit for cylinders 1 and 6, respectively. These codes can lead to misfires, reduced engine performance, and increased fuel consumption. This article will guide you through understanding these codes and potential solutions.
Understanding P0351 and P0356 in Ford Vans
Modern Ford vans utilize a Coil-on-Plug (COP) ignition system, where each cylinder has a dedicated ignition coil controlled by the Powertrain Control Module (PCM). The PCM grounds and ungrounds the coil driver circuit to activate and deactivate the coil, creating the spark needed for combustion.
A P0351 code signifies a problem with the coil driver circuit for cylinder 1, while P0356 indicates an issue with cylinder 6. These codes are triggered when the PCM detects an open or short circuit in the respective coil driver circuits.
Alt: A close-up view of a Ford van engine, highlighting the ignition coils and wiring.
Symptoms of P0351 and P0356
Common symptoms associated with these codes include:
- Illuminated Check Engine Light (MIL): The most obvious sign, indicating a detected fault.
- Engine Misfire: A noticeable rough running engine, often accompanied by a lack of power. The misfire may be constant or intermittent.
- Reduced Fuel Economy: A misfiring engine burns fuel less efficiently.
- Rough Idle: The engine may run unevenly at idle.
Alt: A dashboard display showing an illuminated check engine light, a common symptom of OBDII codes like P0351 and P0356.
Common Causes of P0351 and P0356
Several factors can contribute to these DTCs:
- Wiring Issues: Damaged, corroded, or loose wiring connections in the coil driver circuit are frequent culprits. This includes breaks in the wiring, damaged connectors, or poor contact at the coil or PCM.
- Faulty Ignition Coil: A malfunctioning ignition coil can cause the PCM to detect a fault in the driver circuit.
- PCM Problems: In rare cases, a faulty PCM can be the source of the issue. However, this should be considered only after thoroughly checking other potential causes.
- Short to Voltage or Ground: A short circuit in the wiring can disrupt the coil driver signal.
Diagnosing and Fixing P0351 and P0356
Troubleshooting these codes requires a systematic approach:
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Visual Inspection: Begin by visually inspecting the wiring and connectors associated with cylinders 1 and 6. Look for obvious damage, loose connections, or corrosion.
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Wiggle Test: With the engine running, gently wiggle the wiring harness near the affected coils and the PCM. If the misfire worsens or changes, it suggests a wiring issue.
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Voltage and Signal Tests: Using a multimeter or oscilloscope, check for voltage and signal at the coil connector. This helps determine if the PCM is sending the correct signal and if the coil is receiving it. A lack of signal points to a wiring problem or a faulty PCM driver. A present signal but a misfire indicates a likely bad coil.
Alt: A mechanic using a multimeter to test the voltage at an ignition coil connector, a crucial step in diagnosing P0351 and P0356 codes.
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Continuity Test: Test for continuity in the wiring between the PCM and the coil to identify any open circuits. This requires disconnecting the battery and the PCM connector.
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Component Replacement: Based on the diagnostic results, replace the faulty component – either the wiring, the ignition coil, or (rarely) the PCM. Remember to address any underlying issues that may have contributed to the failure.
Conclusion
Addressing P0351 and P0356 in your Ford van involves a thorough diagnostic process to pinpoint the root cause. By systematically checking the wiring, connectors, ignition coils, and PCM, you can effectively resolve these issues and restore your van’s performance and fuel efficiency. If you are not comfortable performing these tests yourself, consult a qualified mechanic.
