Fuel Composition Sensor (P0178) - SOLVED

[RAMurphy]

On my way into work this morning my check engine light came on. Finished my drive to work, she drove fine with no symptoms at all. Parked and checked the code and was surprised by the P0178 code. I cleared the code. A little research appears to be in my immediate future.

 

[MassHoe04]

At least the fuel composition sensor looks to be a relatively cheap and easy replacement.

 

[RAMurphy]

Concur, will check/read out wires but surely would not be surprised if the sensor is going bad after 20 years on the vehicle and nearly 300K (4300 miles to go) miles on her.

 

[rockola1971]

Concur, will check/read out wires but surely would not be surprised if the sensor is going bad after 20 years on the vehicle and nearly 300K (4300 miles to go) miles on her.

I would not doubt that its bad at that age.

 

[RAMurphy]

Yep, read out the wires last night. Ordered sensor, should arrive on Thursday.

 

[MassHoe04]

Love it when the diagnosis is uncomplicated and repair is easy!

 

[Mudsport96]

Has mpg taken a hit? Sometimes when they fail it goes full alcohol reading so on regular it way over fuels. And timing can get too far advanced, so take it easy driving it.

 

[RAMurphy]

Has mpg taken a hit? Sometimes when they fail it goes full alcohol reading so on regular it way over fuels. And timing can get too far advanced, so take it easy driving it.

It's hard to tell about gas millage taking a hit since I still have over a half tank of gas and I did just complete the TBSS intake install and installed the upgraded BBP tune for this upgrade just days before the P0178 code. Thank you for the advice on driving it easy. No major plans in driving anywhere - just back and forth to work - about 10 miles each way.

 

[RAMurphy]

My part should arrive today, I plan on installing it on Friday. I filled up this morning and I have taken a bit of a hit on gas mileage - nothing major. Could be the the compensator or the new intake/throttle body and the way I was driving based on this upgrade. This was before @Mudsport96 reply. Now I'm babying it.

 

[RAMurphy]

Have replacement part in hand. I really want to get this part installed - so tired of seeing that check engine light on. If I can get off work tomorrow early, I might change it tomorrow.

 

[OR VietVet]

Flex fuel engine fuel composition sensor, seen a few of these set that code here. Parts cannon dictates replacement because of it being inexpensive and easy to install.

 

[iamdub]

I wish I had such a sensor.

*sigh* One day...

 

[Fless]

Flex fuel engine fuel composition sensor, seen a few of these set that code here. Parts cannon dictates replacement because of it being inexpensive and easy to install.

Inexpensive? On RA they are just under $400 each. OE.

 

[OR VietVet]

Inexpensive? On RA they are just under $400 each. OE.

More Information for GM GENUINE 12570260

I had seen threads about this before but my recollection was that it was not that expensive but $371 is not cheap for sure. Good thing he didn't just throw the part at it first and did the testing to be sure. Sorry @Fless

You also need to remember that I am a "thousandaire".

 

[RAMurphy]

Yep, I laughed at the first post about "not expensive" but then again for some that may be cheap. That is why I checked out the wires first. The original has been on there for over 20 years and all those miles, so if you consider the cost per years or per mile - that damn thing is really cheap.

 

[MassHoe04]

Yep, I laughed at the first post about "not expensive" but then again for some that may be cheap. That is why I checked out the wires first. The original has been on there for over 20 years and all those miles, so if you consider the cost per years or per mile - that damn thing is really cheap.

Yeah... Sorry about that comment about being relatively inexpensive!

I don't have FF. I was curious, so I took a quick peek on the interweb and the first things that popped up were like $100.

But for AC Delco... I guess one and done is not terrible for the $371.

NTK was $13 more. Not sure, but there is a very good chance they could have been the OE supplier to GM and making the AC Delco replacements.
If for some reason anyone is not able to get AC Delco, I would be able to put my trust in an NTK as an alternative replacement.

On the bright side, at least it will be an easy job to do!

 

[RAMurphy]

Yeah... Sorry about that comment about being relatively inexpensive!

I don't have FF. I was curious, so I took a quick peek on the interweb and the first things that popped up were like $100.

But for AC Delco... I guess one and done is not terrible for the $371.

NTK was $13 more. Not sure, but there is a very good chance they could have been the OE supplier to GM and making the AC Delco replacements.
If for some reason anyone is not able to get AC Delco, I would be able to put my trust in an NTK as an alternative replacement.

On the bright side, at least it will be an easy job to do!

No issues or worries here.

 

[RAMurphy]

Tahoe is up and ready for this change. I will do this tomorrow. While I'm under the vehicle and under basically the same location, I will also change out the evap canister.

 

[RAMurphy]

Completed the part change. It took about 30 minutes or so - even after depressurizing the fuel lines I still took a bit of a fuel bath. Pretty easy job even in the confined space.

Old compensator:

New part installed:

 

[Joseph Garcia]

Nice work! Thank you for brining this issue to resolution, and posting the result.