P0178..Flex fuel sensor??
 

Hey guys,we have an '04 Tahoe with a flex fuel 5.3. While driving today the engine light came on but was running fine,got home and run the scanner on it and it had the P0178 code showing for the flex fuel sensor. My question is,has anyone had experience with this situation,has anything else caused this very code to come up or is it an indication of the actual flex fuel sensor needing to be replaced? Oreillys has one for $448.00,I dont mind paying for the part as long as that is the cure and not a code from a symptom of something else.Again its been running fine..it has 161.xxx miles on it..Thanks..Phil

Anybody??

Bump...

I think I'd try a fresh tank of gas from a different vendor first... make sure its just not bad gas....

Also if you have not tried, just clear or reset the error to see if it returns...

trying cleaing plug i had the same issue clean the plug with contact cleaner

2004 Flex Fuel Sensor
 

Did you ever find out if it was the contacts or the sensor? I just bought a 2004 Tahoe and I'm having the same issues and like you, I do not want to go and buy a new sensor if there could be an underlying problem I could troubleshoot and not waste the money on a sensor. Thanks, and I know it's been a year but I hope you see this reply.

Welcome to the forum...

You may need to have see what the alcohol content reading is...
I have seen a few post where the alcohol content of the fuel is incorrect and and will cause problems...

I've done a lot of research on this and you have several options.

To replace the the Flex Fuel Sensor, a new one will cost you roughly between $400.00 to about $600.00 and if you are lucky to find a new one on Amazon for about $275.00.

They make a Flex Fuel Replicator if you never use Flex Fuel which is $150.00 but many say it will ruin your vehicle...

Instead, I ran some Flex fuel in the vehicle for the first time ever and a quarter of a tank later, the light went off! However, I ran regular gas on the next fill up and the light came back on. Before I spend money on a new or used Flex Fuel sensor or purchase the replicator, I am going to run flex fuel for a while and see if that will resolve the problem. It may just need several fill ups with flex fuel to fix the problem permanently.

Hope that helps.

I have seen a few instances on new terrains; a replacement sensor has fixed it for all i have worked on.


The diagnostic states that a slug of water going thru the sensor may set this dtc. fuel system drier in the tank and retesting did not fix it...new sensor did.

My 04' burb has the same issue! I keep clearing out the code and tapping on the sensor with a mallet and it goes off for a hundred miles or so. Then the light comes back on and also reads the knock sensors are bad. I had not thought of really running flex fuel. Gas around here just contains 10% ethonal is that the same thing?