I am getting the P0181 code set after being pluged in overnight on my LLY.
Problem
1) The code should no be setting given the over night temperatures. The check engine light is not coming on, so I guess that it is not failing twice in a row.
2) Major lack of power and lost mileage after the code is set. I don't have a code reader but could tell you the instant that it is sets (engine sound changes).
3) Clear code and power/mileage return.
4) It's at the dealer and they have talked to tech line, and were told there is no way the P0181 could cause the power to go down. Dealer has road tested and confirmed the fuel pressure is reduced while the P0181 code is set. Clearing of code allows the fuel pressure to return to correct GM spec levels.

I have changed both the air and fuel filters less than 300 miles ago. I'm also using the winter front when not hauling as the engine temp dives when idleing or coasting to a stop. This is a problem with or with out the juiceinstalled. The engine noise is increased when the juice is turned up above level 0 as it is requesting additional fuel and adjusting the timing.

Has anyone heard of this before? Any ideas would be really appreciated.

Thanx

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in the PI.

Condition/Concern:
01 02 03 04 05 6.6L LB7 LLY Duramax Diesel with a DTC P0181.

Recommendation/Instructions:
Complete published diagnosis for P0181. If the P0181 concern is intermittent, or diagnosis leads to no problem found, verify if the customer is using the winter grill cover blanket and/or the block heater above 0 degrees F. The owners manual does state that the block heater is used at zero degrees or colder. Also determine if the customer parks the vehicle outside or in a heated garage. For 2001 and 2002 model vehicles verify that updated calibration per TSB 02-06-04-058 has been installed. NOTE: Be sure to create a TAC Case and a field product report as Engineering is tracking this information to create a solution for the concern of DTC P0181.

I was given the full document by the dealer and understand what is causing the P0181 to set. I'm having the code set with the winter front, using the block heater while parked outside, and the temperature is below the 0 degrees F.

My bigger concern is the fuel pressure being requested gets knocked down to about 70% of normal. I have started to plug it in above the 0 degree F mark to get a resolution to the loss of power the the GM teck line said could not be happening.

The dealer has confirmed the the fuel pressure that is being delivered is exactly what is being requested via the Tech II. No codes, fuel pressure requested is 100% of GM spec and 100% is being delivered, with code P0181 set, fuel pressure requested 70% of GM spec and 70% of is being delivered.

my truck is doing the same thing it is setting the same code and there is a power loss. i havn't taken it in yet but i plan to.

lbz492

I'm worried that winter is going to end and I will be out of warranty before next winter rolls around. Thats why I'm trying to force the issue now.

Took 4-5 trips to the dealer before they identified the fuel pressure problem.

Kept getting the "CANNOT DUPLICATE CUSTOMER COMPLAINT".

I had the same problem. I plugged in while it was below 20, then left it sit for a day and we had a warm up to the upper 30's. The following day it was in the low 40's when I unplugged, fired it up and took off. Sure enough the light went off and when I had it checked the next day, P0181 was there. Cleared it and it hasn't been back, but I don't plug in until its under 30 now.
Here is a comment I found from another post when I was shooting my code problem:

Conditions for setting P0181- Truck is off for at least 10 hours. At start-up the Fuel Temp (this is return fuel temperature) and the Engine Coolant Temperature are 18 or more degrees different AND the Intake Air Temperature has not decreased by more than 10 degrees after driving for 400 seconds above 15 MPH.

Fit me to a tee. Hope this helps.

lbz492

I'm worried that winter is going to end and I will be out of warranty before next winter rolls around. Thats why I'm trying to force the issue now.

Took 4-5 trips to the dealer before they identified the fuel pressure problem.

Kept getting the "CANNOT DUPLICATE CUSTOMER COMPLAINT".
yea i don't know what to do i posted a quesion in the tech section and they told me to bring it in. i most likely should but are you getting any other codes besides the P0181 because i am getting one on the air intake temp and i think one more but i have to check the truck to find out exactly.

I have yet to see/hear of that condition with the reduced power.. I wonder if there is any other codes set with it? Thats very oddd

I didn't notice reduced power and I only had P0401, P0404, and the P0181. I was accelerating out of a 35mph zone when the light popped on. I took it easy on it since I didn't know what it was, but it didn't seem like I had lost any power.

The truck runs fine until you request additional fuel. i.e. accelerate up a hill, pulling a trailer and accelerating, etc..

Yesterday the only code that was stored is the P0181. I was able to speak to the guy working on it. He told me, with the code set and under load with full throttle that the requested fuel pressure was 70mpa and the fuel being delivered was 70mpa. After he cleared the code, and ran the same on road test, the fuel pressure requested was 160mpa and pressure being delivered was 159mpa.

Even though the temps are not that cold right now (-10 C), I was asked by the mechanic to plug truck in last night. He wanted to do some more investigating of parameters when the code is set. After the code is cleared there is no way to cause it again without waiting the 10 hours and having the proper ambient temperatures.

Again I could tell when the code set after driving it for 5 miles. I may have to leave it over night at the dealers so that they can see if a before and after snap shot can be taken.

Good info. I didn't notice, but then again, I only drive about 2 miles to work, 2 miles to the shop for the Tech II check, etc. and I wasn't towing.

The truck runs fine until you request additional fuel. i.e. accelerate up a hill, pulling a trailer and accelerating, etc..

Yesterday the only code that was stored is the P0181. I was able to speak to the guy working on it. He told me, with the code set and under load with full throttle that the requested fuel pressure was 70mpa and the fuel being delivered was 70mpa. After he cleared the code, and ran the same on road test, the fuel pressure requested was 160mpa and pressure being delivered was 159mpa.

Even though the temps are not that cold right now (-10 C), I was asked by the mechanic to plug truck in last night. He wanted to do some more investigating of parameters when the code is set. After the code is cleared there is no way to cause it again without waiting the 10 hours and having the proper ambient temperatures.

Again I could tell when the code set after driving it for 5 miles. I may have to leave it over night at the dealers so that they can see if a before and after snap shot can be taken.
my truck will keep throwing the codes no mater what i will clear them and then start the truck and turn it off and the same codes will be in the system again. i am going to write down what codes are in there now and i will let you know

here are the codes it puts out P0811, P0812, P0101- mass air flow. then i get all of these unknow ones like P2066, P2067, P2068, P2636 and it just continues on there are about 15 of those unknow codes

lbz492

I'm not sure but I think the P0101 could be a dirty MAF sensor.

Took these off a list that Max Power had posted.
DTC P0101 - Mass Air Flow (MAF) Sensor Performance
DTC P0811 - ?
DTC P0812 - ?
DTC P2066 - Fuel Level Sensor 2 Performance
DTC P2067 - Fuel Level Sensor 2 Circuit Low Voltage
DTC P2068 - Fuel Level Sensor 2 Circuit High Voltage
DTC P2636 - ?

Latest info....
GM admits there is a problem, wow! They say that there is no way that the fuel pressure requested can be changed by the P0181. Dealer has invited them to catch a plane and check it out in person.

GM has asked me to take the winter front off and plug the truck in for the night. Along with the code being set, the intake air temperature was 11 degrees C after driving for 8 minutes. This was on a -8 degree C morning.

that is at least good they admit there is a problem. let me know what they say

I will be following this closely as well.. I just dont see how its possible. I still say underlying issue

Well here it is...

GM's final answer "Do not plug truck in unless temp consistantly below -17 degrees C". Nothing more will be done in regards to my issue.

What a load of crap, I should waste diesel fuel warming the engine up rather than electricity using the block heater. Here in the foothills of southern Alberta the temp can change over night from -20 to +5 celcius, if a chinook wind blows in.

GM has confirmed that the software programming does back the fuel pressure down when this code (P0181) get set. Fuel pressure reduction is related to engine system protection reasons. The fuel pressure requested will increase after the code is cleared or after a given number of cycles. I was not told how many cycles were required, but from what I have seen it has taken over a week of daily driving.

that isn't working for me i having had pluged my truck in for a good two weeks and. i have been checking the code every so often and the last two time i have checked it i am still getting the p0181 code in the system. so it is comming up for me not pluging in the truck

Your truck is the only one I have ever heard off/seen that will back down fuel pressure with that code.....

Hmmmm

ibz492
Some questions GM had.
1) was I using the winter front
2) was I parking in a heated garage
as both can affect the parameters of the three sensors being checked

dmaxallitech
The fuel pressure back down for engine protection was confirmed by both the regional field engineer and I think the dealer said GM platform Tech. The regional field engineer who also only drives Dmax's has had the exact same plugging in and power reduction issues.

no winter cover and no heated garage. i sits outside

Mine has the same code but mine comes on after i have been driving in cold weather for a while, And it did not matter if it was plugged in or not or if the grill cover was on or not because it set the code either way.

DMAX-MIKE,
I would have that checked at the dealer. It sounds like you have issue there. I only popped it once, and I know why, but that code should not set just driving in cold weather or I would see it more often. Of course, that depends on what you call cold, but seeing you are in Michigan, I would imagine you know cold pretty well.
I have adopted a 30 degree rule for plugging in. If its above it and will likely be that way overnight, I leave it unplugged. If its gonna be below it, I plug it in.
So far, I have not duplicated the error I made earlier this year and haven't seen the code again.