Code P0303 is a misfire on cyl 3.

I did a search on this code and read several posts. The most consistent comment is to change plugs and coils. This car also throws code P0015 - exhaust cam position timing over-retarded bank 1.

It is a 2001 S40 1.9 L turbo with 180,000 miles. It runs strong but is stubborn to start.

So far I have swapped the coils and the plugs between 1/4 and 2/3. No change. I noticed that the 1/4 plugs are a good color and the 2/3 are sort of dark.

The car was a donation to a non-profit so I am not sure of its maintenance history or how much time and money we want to put into it. I am thinking I will swap a couple of injectors and do a compression test then decide.

For the Volvo experts I have two questions. How does the system know the misfire is cyl 3; does the O2 sensor see that? And can the cam angle sensor or cam timing device (CVVT?) cause the P0303 code?

 

Someone else here is having these same symptoms. He replaced the CVVT solenoid but still has the miss. I'm thinking you are having similar problems. The ignition system on the 1.9L engine works like the old GM "wasted spark" Distributor-less Ignition System. You have 2 coil-on-plugs plus spark plug wires to the other 2 plugs. The system works by firing 2 cylinders at a time, one on compression, one on exhaust. The ECM knows which cylinder is supposed to fire based on crank and cam position which determines misfire detection. It's not 100% accurate though. Your description of the plug colors tells a whole lot more. Are the dark color plugs oily? or dry sooty? Oily is oil burning and dry sooty is fuel rich (incomplete combustion). I'm thinking you need a tune up and CVVT solenoid. Just a guess. I'd ask around other boards to get more opinions.

 

The generic code isn't a good indication of which cylinder is misfiring on the old S40. There is no Volvo specific code for each cylinder misfiring like there is on other models. With any misfire, its good to start with a set of plugs.

As for the CVVT, if the oil is full and clean, I agree with Hudini. The next step is the camshaft reset valve and then next would be the CVVT hub. Starting with the valve is the way to go because it is cheaper and very easy to replace. However, the hub is pretty common.

 

fix all 3 codes 2 min i looked an changed so much jus to find my connector for coils was not connecting was pushing wires out when i plugged nto coil grab needle nose an push wires onto coil from ba k of plug reset codes an there gone

 

03 s40 p0015 and misfire fix check plugs for coils mi e were pushing wires out of plug when connecting hours of searching and seen the cooper connector sticking out back of plug push them back n an its all fixed