OBDll P0300 code / rough idle

BIGTOW34

MEMBER
2005 VOLVO S60
5 CYL
FWD
AUTOMATIC
76,000 MILES

I have a 2005 volvo S60 2.5T that is throwing a P0300 (P0302 and P0304) OBDII codes. The only time I experience hesitation or bogging is when the vehicle is idling or in park. The RPM's also climb steadily and level off around 2,000 rpm when the car is in park. That led me to believe it may be the ETM but the Volvo dealer told me the 2005 models very rarely had that issue. Any help would be much appreciated.

2 Replies

MHPAUTOS

MECHANIC
31,937 POSTS

P0300 random misfire P0302 misfire cyl 2 P0304 misfire cyl 4.
Start with a tune up check all tune items. Inc compressions, this often finds the fault fore these codes, start here.

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Thursday, July 14th, 2011 AT 1:24 PM

JIS001

MECHANIC
3,411 POSTS

I would agree with mhpautos, I would start with a set of Volvo plugs. Trust me on this. Different plugs and you will get the same problem with random misfires. See way too much. Also remove the boots on the ignition coils to see if they are arcing?
Coils are known to fail on this vehicles. If you are not sure I would recommend you clear the light and move the suspected coils to a different cylinder and road test again. If the misfire code follows that cylinder then you now know the coil is faulty. You can also do that with the fuel injectors. After if you replaced the plugs and swapped coils and injectors and still have a misfire in the same cylinders then you would need to do a compression test and maybe a cylinder leakage test. It is very rare but sometimes the valves start to stick and that will cause a misfire also. Good luck and keep us posted please.