Hi Everyone,

I have a 2001 Volvo S60 with about 115000km on it, and so far all maintenance etc has been up to date. When I started the car, I noticed that the check engine light was on, and the message "emissions system service required" showed up. Previously I have had some intermittent electrical issues so I drove it a bit to see if it would go away, but the light persisted. I turned the car off, and after resting a bit I restarted it, still the same problem.

From what I can tell, the car still drives the same, and isn't making any strange noises. The only thing I noticed that is a bit odd is that lately the car will sometimes seem to stick in a lower gear for too long (it's an auto) and will rev higher than it usually does, before switching to a higher gear and accelerating. Also, there have been a couple times when I put the car into neutral or when I go down a steep hill when the engine will shut off and I have to restart the car. This has only happened twice however for as long as I have had the car, and both times were within the last 4 months or so.

I am not mechanically inclined, and would like to avoid any expensive or unnecessary trips to the dealership or anything, but if necessary I will do it.

If anybody has any advice on what this could be it would be greatly appreciated, along with any tips on how to fix it.

Thanks!

 

When i Buy mine, it keeps getting P0304.
I swapped coil packs 4, with 1, and the problems appeared on cyl 1, then you can be sure that there's a problem with the coil pack.
It cost near 60 bucks!

 

To the first poster, it could be that the secondary O2 sensor is deficient. If the mileage is good, nothing to worry about. That also happens when the exhaust flexible, near the oxygen sensor gets busted, causing air to confuse the sensor.