01 2500 Hd P300 Code Again!

hd2500ny · October 13, 2010

Hi, I recently got a 01 2500hd auto, 6.0 vortec, and I love it, however I have noticed the "service engine soon" light flashes while driving down the highway. It happens between 60

and 75 mph, anything above or below it does not do it. It starts in the 2500 rpm range in drive only. The light does not come on when I get to 2500 rpm or above when

in 1,2,or 3. The computer will not store the code, it only registers when I have the reader hooked up while driving, and only when the light is flashing I have been

reading alot here and other places and it seems I am not the only one with this problem. The code is p300 random misfire always p 300, no specific cylinder

registered by the reader. There is no noticable skipping or loss of

power when driving, it runs great, but the light is irritating as hell and I cant help but imagine big, big problems if I dont fix.

truck has 106k on it. I have changed the plugs and wires, changed the PCV valve, also new air filter and cleaned the MAF and the light still comes on. I am relatively new at do it yourself, and

I do not have the money or skills to randomly replace parts. For those with a budget, what should be my best next step before going to the shop, Cam sensor,

trans speed sensor, EGR, exaust manifold leak? Any suggestions?

Kirkathon25 · October 13, 2010

when you figure it out let me know ive got the exact same problem, i did all the stuff you did, im going to check my fuel pressure next im just too cheap to buy a gauge they are like 50 dollars, but if that doesnt work im going to clean my fuel rails and then egr valve, other than that i have no idea

hockeypro1411 · October 13, 2010

I still have the same issue. I just ignore the stupid ass light flashing. A few people on here have reported that having a dealer do a crank re-learn will take care of this issue. However, for some people (myself included) the crank re-learn does nothing.

hd2500ny · October 14, 2010

I still have the same issue. I just ignore the stupid ass light flashing. A few people on here have reported that having a dealer do a crank re-learn will take care of this issue. However, for some people (myself included) the crank re-learn does nothing.

I had a mechanic look today, he said it is carbon buildup on the valves and injectors that is causing this problem.He did not look at the truck, only said he has dealt with the same issue several times before on 2500hd's. He is one of the more reputable repair shops in the area. I just changed the fuel filter today and it was shot. Of course the shop wants $700 to do the work. I dont know how to do this myself nor do I have the time. Is there any fuel or engine treatment out there that actually works fairly well- I would like to try that first.

I also went to the dealer to ask bout the crank relearn. Naturally they want to run diagnositcs first ( which I am not against) but they want $100 to do that, and than an extra $100 IF they need to re learn the crank which can be done with the same stuff they are using to run the diagnostic.

I am not sure what I will do next, I dont want to cough up the cash if I dont have to.

desrtrat · October 14, 2010

I still have the same issue. I just ignore the stupid ass light flashing. A few people on here have reported that having a dealer do a crank re-learn will take care of this issue. However, for some people (myself included) the crank re-learn does nothing.

I had a mechanic look today, he said it is carbon buildup on the valves and injectors that is causing this problem.He did not look at the truck, only said he has dealt with the same issue several times before on 2500hd's.

you could try some Sea Foam in the fuel tank. put 2 cans in when your about 3/4 full, and run it down to a little less than 1/2. then fill up. 1 can would properly do, but if it has never been done before the extra will help. or you can run 1 can through the intake, and one in the fuel tank..

http://www.seafoamsales.com/how-to-use-our-products.html

good luck

hd2500ny · October 14, 2010

I still have the same issue. I just ignore the stupid ass light flashing. A few people on here have reported that having a dealer do a crank re-learn will take care of this issue. However, for some people (myself included) the crank re-learn does nothing.

I had a mechanic look today, he said it is carbon buildup on the valves and injectors that is causing this problem.He did not look at the truck, only said he has dealt with the same issue several times before on 2500hd's.

you could try some Sea Foam in the fuel tank. put 2 cans in when your about 3/4 full, and run it down to a little less than 1/2. then fill up. 1 can would properly do, but if it has never been done before the extra will help. or you can run 1 can through the intake, and one in the fuel tank..

http://www.seafoamsales.com/how-to-use-our-products.html

good luck

I have tried several products in the gas tank, I will try the sea foam. This might be a dumb question but as I am new to DIY, how do I run a can through the intake?

hd2500ny · October 15, 2010

when you figure it out let me know ive got the exact same problem, i did all the stuff you did, im going to check my fuel pressure next im just too cheap to buy a gauge they are like 50 dollars, but if that doesnt work im going to clean my fuel rails and then egr valve, other than that i have no idea

am going to bite the bullet and have the dealer run the computer diagnostic today. Maybe its wishful thinking but I am hoping for the crank re learn. The tires I have are bigger than oem ( I have 265/75 r 16, oem is 245/75 r16) and the transmission looks to me like it is all shiney and new compared to the rest of the underside of the truck, so maybe a new/rebuilt one. Maybe one or both of these things could be causing the crank needing to be re learned, as such causing the p 300 code? Any ideas?

hd2500ny · October 15, 2010

I still have the same issue. I just ignore the stupid ass light flashing. A few people on here have reported that having a dealer do a crank re-learn will take care of this issue. However, for some people (myself included) the crank re-learn does nothing.

I had a mechanic look today, he said it is carbon buildup on the valves and injectors that is causing this problem.He did not look at the truck, only said he has dealt with the same issue several times before on 2500hd's.

you could try some Sea Foam in the fuel tank. put 2 cans in when your about 3/4 full, and run it down to a little less than 1/2. then fill up. 1 can would properly do, but if it has never been done before the extra will help. or you can run 1 can through the intake, and one in the fuel tank..

http://www.seafoamsales.com/how-to-use-our-products.html

good luck

Just a question: I read the sea foam link, it says something specifically about vortec engines. I am not sure where to use the seafoam for the intake. Would it still be the hose attached to the PCV valve like other engines? Seafoam site says to consult a mechanic for vortec engines if you are not sure...

hd2500ny · October 19, 2010

I still have the same issue. I just ignore the stupid ass light flashing. A few people on here have reported that having a dealer do a crank re-learn will take care of this issue. However, for some people (myself included) the crank re-learn does nothing.

I had a mechanic look today, he said it is carbon buildup on the valves and injectors that is causing this problem.He did not look at the truck, only said he has dealt with the same issue several times before on 2500hd's.

you could try some Sea Foam in the fuel tank. put 2 cans in when your about 3/4 full, and run it down to a little less than 1/2. then fill up. 1 can would properly do, but if it has never been done before the extra will help. or you can run 1 can through the intake, and one in the fuel tank..

http://www.seafoamsales.com/how-to-use-our-products.html

good luck

Just a question: I read the sea foam link, it says something specifically about vortec engines. I am not sure where to use the seafoam for the intake. Would it still be the hose attached to the PCV valve like other engines? Seafoam site says to consult a mechanic for vortec engines if you are not sure...

Ok the dealer checked it out, they are saying that I need a new fuel pump. Is this real hadt to change out yourself? I know I would have to drop the gas tank but if the whole procedure is not to complex, I would much rather do it than pay 675.

hd2500ny · October 19, 2010

I still have the same issue. I just ignore the stupid ass light flashing. A few people on here have reported that having a dealer do a crank re-learn will take care of this issue. However, for some people (myself included) the crank re-learn does nothing.

I had a mechanic look today, he said it is carbon buildup on the valves and injectors that is causing this problem.He did not look at the truck, only said he has dealt with the same issue several times before on 2500hd's.

you could try some Sea Foam in the fuel tank. put 2 cans in when your about 3/4 full, and run it down to a little less than 1/2. then fill up. 1 can would properly do, but if it has never been done before the extra will help. or you can run 1 can through the intake, and one in the fuel tank..

http://www.seafoamsales.com/how-to-use-our-products.html

good luck

Just a question: I read the sea foam link, it says something specifically about vortec engines. I am not sure where to use the seafoam for the intake. Would it still be the hose attached to the PCV valve like other engines? Seafoam site says to consult a mechanic for vortec engines if you are not sure...

Ok the dealer checked it out, they are saying that I need a new fuel pump. Is this real hadt to change out yourself? I know I would have to drop the gas tank but if the whole procedure is not to complex, I would much rather do it than pay 675.

As I said, the dealer did check things with a tech II and said I need a new fuel pump, I dont doubt this much as I do have a high pitched whirring zzzzz noise by the fuel tank area. The interesting thing is that after the tech did whathever with the tech II, the check engine light does not come on anymore at all, even in the speed range that it used to. I doubt that resetting the code would do it if the problem is still there, maybe the tech hooked me up and did some tuning? Crank relearn?? hard to say except that the light does not come on anymore!

hockeypro1411 · October 20, 2010

I still have the same issue. I just ignore the stupid ass light flashing. A few people on here have reported that having a dealer do a crank re-learn will take care of this issue. However, for some people (myself included) the crank re-learn does nothing.

I had a mechanic look today, he said it is carbon buildup on the valves and injectors that is causing this problem.He did not look at the truck, only said he has dealt with the same issue several times before on 2500hd's.

you could try some Sea Foam in the fuel tank. put 2 cans in when your about 3/4 full, and run it down to a little less than 1/2. then fill up. 1 can would properly do, but if it has never been done before the extra will help. or you can run 1 can through the intake, and one in the fuel tank..

http://www.seafoamsales.com/how-to-use-our-products.html

good luck

Just a question: I read the sea foam link, it says something specifically about vortec engines. I am not sure where to use the seafoam for the intake. Would it still be the hose attached to the PCV valve like other engines? Seafoam site says to consult a mechanic for vortec engines if you are not sure...

Ok the dealer checked it out, they are saying that I need a new fuel pump. Is this real hadt to change out yourself? I know I would have to drop the gas tank but if the whole procedure is not to complex, I would much rather do it than pay 675.

As I said, the dealer did check things with a tech II and said I need a new fuel pump, I dont doubt this much as I do have a high pitched whirring zzzzz noise by the fuel tank area. The interesting thing is that after the tech did whathever with the tech II, the check engine light does not come on anymore at all, even in the speed range that it used to. I doubt that resetting the code would do it if the problem is still there, maybe the tech hooked me up and did some tuning? Crank relearn?? hard to say except that the light does not come on anymore!

The fuel pump is pretty simple to replace. I'd just take the bed off instead of drop the tank to get at it.

tcalb2 · February 4, 2011

Did the fuel pump fix the trouble code. I have the same code going on my 2500hd and my fuel gauge has been acting funny for a while now. I think the fuel filter for my truck is in the tank tho, I'm not sure. its an 07 classic

pmax · February 8, 2011

I've got same problem on my '01 HD. It has 117,000 on the clock. I replaced fuel filter at about 110,000. Recently replaced wires, plugs, fuel filter, EGR, air filter and exhaust manifolds. Problem persists.

rgriffin · February 18, 2011

Add one more to this club. I have an 02 2500hd and I'm having the same issues. On top of the misfires, my torque convertor is unlocking evey time the PCM senses a misfire-- even if no code is stored. When I drop the rpm's down to about 2100 for about a minute and a half it will lock back up. This is on the expressway doing 74mph. 74 mph it usually runs at 2300rpm in lock-up and at about 2700rpm unlocked. When I slow to about 64mph for a mile and a half it will lock back up and then unlock again when I reach 75mph. Then I'll usually get a flashing MIL with a p0300 code stored. It's driving me nuts. New Throttle Position Sensor, Engine Coolant Temp Sensor, Manifold Absolute Pressure Sensor, EGR, Mass Air Flow Sensor, Vehicle Speed Sensor, AC plugs, AC wires, AC Delco Cam Position Sensor, 2 Delphi coils on #5 & #8 cylinders. According to the freeze-frame on my Actron reader the Fuel trims on bank 3 and 4 are way high-- both long and short term. The long terms are in the +80% range! Fuel pressure regulator?

pmax · February 28, 2011

I had an interesting development yesterday. I was warming up the truck preparing to plow. When I got in there was an overwhelming smell of comustion gas of some sort I immagine. I vented the truck and it disipated. When I got in and put it into gear that "service engine" light came on for a few seconds. It went out but the truck idled a little rough for a while. The light never came back after that. Catalytic converter isuues maybe?