Hi All. I have a p0300 (random misfire) code that won't go away. I changed my plugs the other day. I am going to clean my Throttle Body as well. I was told that maybe I should look at changing my o2 sensors pre-cat. I called the stealership and they said I have 4 sensors, 2 pre, 2 post. They were asking $90 a sensor!!!!! I found sensors on rockauto.com for $19 each. I was told to look at the Bosch as they are "exact fit". http://www.rockauto.com/catalog/raframecatalog.php?ck[viewcurrency]=USD&ck[ID]=0&ck[idlist]=0 Do you guys have other suggestions to try other than the o2 sensor? And as I am a noob, where are the 2 located? Are there other sensors that could be affecting this and causing this code to show up? It starts fine, then when I drive to a stop light, it about stalls, then I restart it and it runs fine the rest of the time. Someone else mentioned needing a flash from the dealer maybe. Oh and yes I did reset my computer after the plug change. Any help would be great!!

 

It could be the Pre cat o2 because this one controls fuel air mix but for a misfire? hmmm if you just changed plugs hopefully to Champion Coppers then the next place i would look is to Coils,if you have a multimeter check to see that they are all close to the same.
After that id think of o2 sensors and maybe even a CAT clogged.

 

Thanks, yeah you were the one who put me going to the o2 sensors at rockauto. Thanks for that by the way, the price is amazing. I will have to see if my dad or friend has a multimeter.

 

LOL Good they need as much bussiness as they can get! Prices that cheap everyone should know about them! and Since it stalls when idiling maybe it could be o2

 

I just don't get why it only about stalls once, then I turn it off and back on, and its good to go for however long I drive it.

 

DONT GET BOSCH!! They have issues. I've put those into a couple other peoples chryslers (although admittedly not a ram) and they throw codes. Get the ntk ones, they are the oem and basically the same price, i think maybe they are 22$. Make sure you replace all 4 if you do the O2's. They are right on top of your exhaust before and after your cat, its hard to miss.

 

I have to agree with this. I think Weedahoe is the ONLY member who has ever put Bosch O2 sensors on their Ram and NOT gotten codes. Mopar or the NTK (NGK sensor division) work fine.

Another common cause of multiple misfire codes on these trucks besides plugs/coils would be an exhaust leak - and we ALL know how those exhaust manifold bolts like to break - especially the rear two. You need to look there as well IMO...

 

This could also be related to your stalling if you're losing compression

 

ok so two questions. how do I check for the exhaust leak? just feel for air coming out? and where so I put the multimeter to read the coils? sorry I'm learning


Posted from Dodgeforum.com App for Android

 

If it has the hook option to read the wires, then read those with the truck running(I dont know how to explain it but a hook or loop at the to of the meter that wraps around the wire). If it just has the two leads coming out(Positive and Ground) un plug the connector where it goes into the coil and start the truck they dont have to be on any certain prong just + on one - on the other