My check engine light has been on (not blinking, just steady) for a month or so. Technician at S ubaru dealer says third cylinder is misfiring and I need to replace the ignition coil; they recommend replacing spark plugs and wires, as well. The ignition coil replacement costs $350; the spark plugs and wires $200. Is this a necessary repair? What happens if I don't do it?Is it dangerous to drive with this condition, or "just" bad for engine-- what are the consequences of letting this go? Thanks for advice.