Reviews of OEM Volvo spark plug

He replaced the spark plugs and tested all of the ignition coils. Still had error code.

This particular car, like a number of vehicles with V6 engines, requires that the intake manifold be removed in order to access one bank of cylinders to replace the spark plugs. This is why it costs so much to do the work.

I'm chasing a cylinder 3 misfire in my S40 right now. I'd put new coils and plugs in two summers ago, but when I pulled that one to check it, the coil came apart and the plug electrode was heavily eroded.

Even the OEM Volvo plugs are good for about 40K miles. 99% chance it’s the coil. Every single time I have had a misfire, it’s been a coil, so much so that I literally keep 1-2 spare new ones floating around at all times.

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But yea the electrodes say everything. The quality difference is massive. And some cars a very picky about spark plugs. I had a Volvo that I had to put actual Volvo plugs in for it to run correct. No joke it solved a 30 second crank poor gas mileage and severe stumble and misfire when coming into boost.

I have the similar motor as the 740 you posted. These cars are super simple to work on and nothing major really goes wrong with them. If you do run into issues you can find DIY help on the internets and parts are dirt cheap.