P0301, P0442 and high pitch buzz

kevabar · Post by **kevabar** » 29 Aug 2012, 12:21

2004 XC70 (with 145k) has a P0301 (Cylinder #1 misfire), P0442 Evap (small leak), a noticeable fuel odor and a high pitched buzz coming from the top of the engine (ie: i can hear it if i put my ear near the oil fill cap). oh and the CEL is on too.

Last Saturday, the display gave me a loose gas cap warning. I tightened it up and drove around town with no problems.

Today, when it was started, it ran rough and had a noticeable odor (neither of which were there yesterday). Also, after the car was turned off and I was about to close the hood, I heard a slight buzz mentioned above.

I think replacing the vacuum hoses might be an easy and cost effective fix for P0442. Heck, there are 8 years old anyway. The buzzing has me stumped? What should I look for?

Post by **igel513** » 29 Aug 2012, 16:39

Check the fuel pump located under the rear seat. It may be leaking - there's a recall on faulty pumps so call the dealer and give them your vin and they'll tell you if your car is included in that recall. The buzzing sound could be the solenoid on top of the engine- left side near the TB. It happened on my 03 S60 and am just assuming your engine also has that solenoid. Remove the top TB cover and you'll see the part I'm referring to.

kevabar · Post by **kevabar** » 29 Aug 2012, 19:49

The codes are now P0300, P0301, P0302, P0442, CEL, fuel odor and buzzing. I took off the 2 black TB covers. I can't pinpoint the buzzing. The hut will have to continue tomorrow.

Post by **jblackburn** » 29 Aug 2012, 20:29

The buzzing may be the EVAP valve on the radiator shroud near the battery. Unplug the valve and see if it shuts up. This valve being stuck or defective would definitely explain the p0442 - as would broken EVAP canister hoses.

If its not that one, unplug the idle control valve and see if that's it.

Post by **DGM** » 30 Aug 2012, 06:06

You have cylinders #1,#2 with misfiring codes. I would suggest to investigate this condition first to see what is wrong. To help find this tutorial on how to do it.

https://www.matthewsvolvosite.com/forums ... =9&t=27232

If fuel isn't burned completly you will have fuel smell.

The EVAP code "small leak" would not normally affect idling. To me it is a separate issue. It may have been only a loose gas cap or something has started to deteriorate as mentioned.

kevabar · Post by **kevabar** » 30 Aug 2012, 13:35

I switched coil #1 with #5 (closest to driver's side = #5). I switched #2 with #4. I cleared the codes, started the engine and it still runs rough (but no CEL). I drive 5 miles back to work. Less than a mile into my drive, the CEL comes back.

The codes are now: P300, P303 and P305 (I expected 305).

I think #1 coil (now in #5) is causing issues in the other cylinders and after replacing #1, I will have no more codes (related to coils). Can one coil cause excessive stress on other cylinders causing extra codes?

btw I still have that buzz that seems to be coming from the fire wall area or backside of the engine. No buzz from the radiator shroud area.

kevabar · Post by **kevabar** » 30 Aug 2012, 19:22

Update: I returned all ignition coils to their proper locations and then replaced #1. The engine purrs, no CEL and no buzz. I drove a few miles and so far so good. Thanks to jblackburn, igel513 and DGM for the links!