[dtsimpala]

Hello Folks,

I successfully changed my thermostat, but now I'm getting a P0178 code "Fuel Composition Sensor Circuit Low". What will happen if I continue to drive with the car throwing this code? I've cleared the code but it's come back.

I think when I was changing the thermostat, I tugged a little too hard on the menacing wirebundle, and possibly tore something up.

Any guidance is greatly appreciated.

 

[reubenswinks]

This is just for the flex fuel part of your vehicle. If you run e85, you would certainly want this fixed I would think. If you run regular gas, I am not sure it is that important? I would imagine with the sensor not reading correctly, the computer defaults to the normal fuel mapping. Little bit of speculation on my part I guess, but unless you notice it running weird (i.e down on power, knocking, misfiring), I wouldn't worry too much about driving it until its fixed. As for fixing it, it could be a wiring issue, or maybe you just got unlucky with the timing and the sensor went bad. Swapping the sensor doesn't look too hard, but its not the cheapest (~$70 on rockauto) to just replace without knowing if its wiring or not. Here is its location

Not sure if you have access to a code reader that does live data, but if you could monitor the fuel composition, you could try wiggling the wiring harness bundle to see if it creates any sporadic readings.

 

[Brhatweed]

Being LOW I'm wondering if it's shorted like maybe pinched under a bolt or thermostat housing... done this a few time myself

 

[dtsimpala]

I neglected to mention that while cleaning the thermostat gasket, I was using a razor blade that I lost grip of and it went flying. When I found it, it was lying near the wire bundle in question. After retrieval, my car never threw that code again.

Note to self, do something to retain the blade so it can't be dropped or tossed while changing grip