Volvo S40 2001 fourth cylinder misfire issue, possible coil failure on Volvo S40

Some Volvo S40 2001 owners report experiencing fourth cylinder misfire issues, often suspected to be due to a faulty coil. Accurate diagnosis is essential, as confirming a coil failure can be achieved by swapping the suspected faulty coil with a known good one and monitoring live misfire data. Repair costs for addressing this misfire can vary, with spark plug or ignition coil replacements ranging from $100 to $300, while cleaning or replacing fuel injectors may cost between $50 and $200. Additionally, owners should be aware that other potential causes, such as wiring issues, ECM problems, or mechanical issues within the cylinder, could also lead to misfires. If a coil failure is confirmed, replacing the faulty coil and ensuring proper connections is crucial for resolving the issue effectively and preventing further complications.