P0358 2002 Ford F150 Code - Ignition Coil 'H' Primary/Secondary Circuit Malfunction

P0358 indicates an issue with the ignition coil "H" primary or secondary circuit, meaning there’s a malfunction in the electrical circuit responsible for firing the spark plug in cylinder 8.

Common symptoms include engine misfires, rough idling, reduced power, poor fuel economy, and potentially an illuminated check engine light.

The most common causes are a faulty ignition coil, damaged wiring or connectors in the coil circuit, a bad spark plug, or a failing powertrain control module (PCM).

In Ford’s cylinder numbering system, cylinder 8 is located on the passenger side, closest to the firewall. Ignition coil "H" corresponds to this cylinder.

Driving with this code is not recommended as it can lead to engine misfires, reduced performance, and potential damage to the catalytic converter over time.

Start by inspecting the ignition coil and its wiring for damage or corrosion. Replace the ignition coil or spark plug if necessary. If the issue persists, further diagnosis of the PCM or wiring harness may be required.

Use a multimeter to check the resistance of the coil. Compare the readings to the manufacturer’s specifications. Alternatively, swap the coil with another cylinder to see if the problem follows the coil.

Yes, a worn or damaged spark plug can cause excessive resistance in the ignition circuit, triggering the code.

Common tools include an OBDII scanner, multimeter, spark plug socket, and basic hand tools for inspection and replacement work.

Clearing the code without addressing the underlying issue will not resolve the problem. The code will likely return until the malfunction is properly repaired.