How to fix SES P0178 and P0179 - Flex Fuel Sensor

[Hucko]

What is Flex Fuel?

A flexible fueled vehicle (FFV) has a single fuel tank, fuel system, and engine. The vehicle is designed to run on unleaded gasoline and an alcohol fuel (usually ethanol) in any mixture. The engine and fuel system in a flex-fuel vehicle must be adapted slightly to run on alcohol fuels because they are corrosive. There must also be a special sensor in the fuel line to analyze the fuel mixture and control the fuel injection and timing to adjust for different fuel compositions.

What Service Engine Soon codes does it throw?

P0178 and P0179 are directly related to the sensor its self

P0178 - Fuel Composition Sensor. Sensor Circuit Low Volts
P0179 - Fuel Composition Sensor. Sensor Circuit High Volts

Can this really effect anything?

Yes, It can cause your truck to run richer then it should.

In my case I was also throwing an HO2 Sensor (P0141), this went away after I replaced the Flex Fuel sensor.

How much does this sensor cost and what is the part number?

There are 2 part numbers (both are the same part):
The first one: 12568450 (older part number)
The second one: 12570260 (most recent)

From a GM dealer this part will run $613
From GMPartsDirect.com it runs $350

dealer will charge around $900-1100 to fix!

PM ME for details on finding the older part number cheaper.

Where is the sensor located and what does it look like?

Passenger side, Front frame rail. Right behind the wheel well.

It has 2 fuel lines comming out of it and 1 power.

Actual pic from engine area:


Stock picture of the part:



What kind of tools are needed to replace this myself?

Size 13mm Socket
Fuel Line disconnects ($5 - $10)

I Circled the correct one to use:


How long does it take and is it easy?

Yes it is easy, and it takes about 2-3 hours depending on how you go about getting to it. Take your time and be careful! (a little bit of gas will come out of those lines)

I pulled off the passenger side wheel and went thru the wheel well with a friend under the truck helping.


I hope I was of some help! PM ME with your questions!

[Hucko]

http://www.s10forum.com/classifieds/...cat=500&page=1

[TwentyInches]

Quote: Originally Posted by Hucko

What is Flex Fuel?

A flexible fueled vehicle (FFV) has a single fuel tank, fuel system, and engine. The vehicle is designed to run on unleaded gasoline and an alcohol fuel (usually ethanol) in any mixture. The engine and fuel system in a flex-fuel vehicle must be adapted slightly to run on alcohol fuels because they are corrosive. There must also be a special sensor in the fuel line to analyze the fuel mixture and control the fuel injection and timing to adjust for different fuel compositions.

What Service Engine Soon codes does it throw?

P0178 and P0179 are directly related to the sensor its self

P0178 - Fuel Composition Sensor. Sensor Circuit Low Volts
P0179 - Fuel Composition Sensor. Sensor Circuit High Volts

Can this really effect anything?

Yes, It can cause your truck to run richer then it should.

In my case I was also throwing an HO2 Sensor (P0141), this went away after I replaced the Flex Fuel sensor.

How much does this sensor cost and what is the part number?

There are 2 part numbers (both are the same part):
The first one: 12568450 (older part number)
The second one: 12570260 (most recent)

From a GM dealer this part will run $613
From GMPartsDirect.com it runs $350

dealer will charge around $900-1100 to fix!

PM ME for details on finding the older part number cheaper.

Where is the sensor located and what does it look like?

Passenger side, Front frame rail. Right behind the wheel well.

It has 2 fuel lines comming out of it and 1 power.

Actual pic from engine area:


Stock picture of the part:



What kind of tools are needed to replace this myself?

Size 13mm Socket
Fuel Line disconnects ($5 - $10)

I Circled the correct one to use:


How long does it take and is it easy?

Yes it is easy, and it takes about 2-3 hours depending on how you go about getting to it. Take your time and be careful! (a little bit of gas will come out of those lines)

I pulled off the passenger side wheel and went thru the wheel well with a friend under the truck helping.


I hope I was of some help! PM ME with your questions!

How the hell do you get the Actually sensor off the hose? i took of the clips and the damn thing wont come out?

[n8rsk8r]

so...... I just changed my engine over. The new engine (2001) USED to be flex fuel. I used the old intake/fuel setup that was with my old engine (1999) After reading the description above... with the sensor that sits inline on the fuel line that reads fuels... can one get better gas mileage than the typical crappy gas mileage that using ethanol usually means with a regular fuel system???

[Hucko]

Quote: Originally Posted by n8rsk8r

so...... I just changed my engine over. The new engine (2001) USED to be flex fuel. I used the old intake/fuel setup that was with my old engine (1999) After reading the description above... with the sensor that sits inline on the fuel line that reads fuels... can one get better gas mileage than the typical crappy gas mileage that using ethanol usually means with a regular fuel system???

The flex fuel means you can use E85 which does not get better gas milage and also removes a few horses. I think that is what you're asking anyway.

[n8rsk8r]

yeah, sorry just reread my post! LOL yeah that is what I meant. Hmm. Okay, that makes sense.

[Sandite5]

Bringing up an old thread I know, but I have the exact same codes tripping off.

I'd rather not have to buy a $300 sensor. Does anyone think there might be another way around it? I don't much care if I lose the Flex-Fuel feature at all as there are no stations around here anyway.

[crazystang26]

Ive been searching for hrs on the net looking for info on this same exact problem, Dose anyone know where i can get this part cheap? thanks

[Mikey08]

Quote: Originally Posted by Sandite5

Bringing up an old thread I know, but I have the exact same codes tripping off.

I'd rather not have to buy a $300 sensor. Does anyone think there might be another way around it? I don't much care if I lose the Flex-Fuel feature at all as there are no stations around here anyway.

pull out your cluster and pop out the SES light :P

[BaggedSonoma]

So am I right to say that there is no way to bypass this sensor so I can clear the SES light and get my new truck (2000 GMC Snoma) to pass smog. (Stupid California smog laws!)

[Sandite5]

Quote: Originally Posted by BaggedSonoma

So am I right to say that there is no way to bypass this sensor so I can clear the SES light and get my new truck (2000 GMC Snoma) to pass smog. (Stupid California smog laws!)

Yea I've been looking for all sorts of stuff as well. I was hoping to bypass or at least fool the computer into thinking it's running alright.

I get about 22mpg @ 65-70mph. I run about 80-90% highway miles on it per week and it pisses me off to see V8's getting better mileage than I do!!

[GeorgesBlazah]

22mpg on the hwy sucks I get 30-31

[S15vortecpwr]

i get 25-27

[colabear]

Quote: Originally Posted by Sandite5

Yea I've been looking for all sorts of stuff as well. I was hoping to bypass or at least fool the computer into thinking it's running alright.

I get about 22mpg @ 65-70mph. I run about 80-90% highway miles on it per week and it pisses me off to see V8's getting better mileage than I do!!

The problem for fuel economy is the weight to HP of these trucks. My truck's curb weight is 3950 lbs. I'm pushing that around with a motor that only puts out 120HP at the flywheel. Do the math and pay at the pump. My friends Nissan extended cab with a V6 gets 28/32 but it only weights 3600.

[Hucko]

to be honest, 300$ is not much, just do it yourself. The dealerships want to charge over 1200$ for the repair.

[colabear]

Quote: Originally Posted by Hucko

to be honest, 300$ is not much, just do it yourself. The dealerships want to charge over 1200$ for the repair.

It's a little more now. Didn't you get a deal on e-bay for your parts? I think mine cost around $500 or maybe a little more when I replaced it last year (and that was because by daughter was working at a Chevy dealership at the time).

[BaggedSonoma]

My father inlaw is a service manager at a GM dealer and his ot is $410

[Prostreet68]

Quote:

The flex fuel means you can use E85 which does not get better gas milage and also removes a few horses

Wondering where you got your facts on this? From dyno testing...the use of E85 will increase hp instead of removing. E85 octane is rated between 100-105 when gas is between 87-91 or 92 depending on what part of the country your from..

Prostreet68
R&R Racing Enterprises Inc

[SickSpeedMonte]

we have 93 here in MD

and running high octane doesnt mean squat if you dont need it. It slows the burn to prevent detonation, and actually makes less power than 87 if your motor doesnt detonate on 87.

I have never seen back to back E85 vs pump gas dynos, but unless it was a high compression motor, i really doubt it. E85 has a 27% lower energy content than gasoline, and you generally get lower fuel mileage as well.

[Prostreet68]

68 Chevelle 350 cid,9.5:1,fuel injected,turbo charged made 93hp more on E85 than it did on pump gas with back to back dyno pulls...

Prostreet68
R&R Racing Enterprises Inc

[SickSpeedMonte]

9.5:1 plus boost. Prone to detonation already, so it greatly benefits from the octane. It just all depends on the setup.

PS... any pics of said turbo chevelle??? Sounds sick.

[Prostreet68]

I see if I can get some pictures from the owner....Yes it is a NASTY machine to drive on the street!
Oh I forgot to mention...this was done on 6lbs of boost! Good fuel injection system will take care of that ping factor and back the timing off...
Prostreet
R&R Racing Enterprises Inc

[Hammermechanic]

There is a company on ebay called tselectronics that sells a device called a flex fuel replicator. All you do is unplug the flex fuel sensor and plug in this box. I'm getting 8 to 10% better gas mileage with it too. Its $150 but that beats the heck out of $400, plus it pays for itself in fuel savings.

[colabear]

Quote: Originally Posted by Hammermechanic

There is a company on ebay called tselectronics that sells a device called a flex fuel replicator. All you do is unplug the flex fuel sensor and plug in this box. I'm getting 8 to 10% better gas mileage with it too. Its $150 but that beats the heck out of $400, plus it pays for itself in fuel savings.

Can you post a link to their site? I did an e-bay search and could not find them.

Thanks.

[King_Ice_Flash2]

http://cgi.ebay.com/ebaymotors/_Car-Truck-Parts-Accessories__Flex-Fuel-Sensor-Replicator-GM_W0QQitemZ280258926313QQadnZCarQ20Q26Q20TruckQ20 PartsQ20Q26Q20AccessoriesQQadiZ2865QQcmdZViewItem? hash=item280258926313&_trkparms=39%3A1|65%3A1|240% 3A1318&_trksid=p4506.c0.m245

[Prostreet68]

That part is all well and good execpt where it states that it leans out the mixture. From where I come from lean mixture is a recipe for burnt valves. Yes you may get better mileage but your performance will suffer and chances of doing other damage. Might read the small print on the box.

Rick
R&R Racing Enterprises Inc

[crazy_cjenkins]

Theres a few sensors on ebay right now for $75 bucks but there used, thats even cheaper than the replicator and sure beats the heck out of 400+ for a new one!

I've been runing on E85 for the last few months now and not really notice any differece in power or millage and at $2.89 here in Missouri its .60 cheaper its a no brainer!

[ohsolos10]

Quote: Originally Posted by Hammermechanic

There is a company on ebay called tselectronics that sells a device called a flex fuel replicator. All you do is unplug the flex fuel sensor and plug in this box. I'm getting 8 to 10% better gas mileage with it too. Its $150 but that beats the heck out of $400, plus it pays for itself in fuel savings.

has anyone else tried this i am so tired of seeing my check engine light and if this will fix the problem then it seems well worth the price better mpg is just a perk at this point

[Hammermechanic]

Quote: Originally Posted by ohsolos10

has anyone else tried this i am so tired of seeing my check engine light and if this will fix the problem then it seems well worth the price better mpg is just a perk at this point

I'm happy with the flex fuel replicator I got on ebay. It doesn't lean out the mixture enough to even notice. Even if it did, the oxygen sensor would bump the mixture back up. Anyways, good luck.

[manulin_matty_c]

if you dont plan on runing e85 do u need to replace

[Chamorro]

So the only way to fix the P0178 code is to replace the sensor altogether correct? Is there any other way to bypass this electronc predicament?


Mark