Pinhole coolant leak causing bad gas mileage???

[Cool Mr Steve]

Wow, I haven't posted on here in a long while... Anyway, I've been having some issues with my gas mileage. I generally get 25-27mpg, but at my last fill-up I was getting 19-20. Onto the coolant leak; I smelled coolant while I was driving and when I reached my destination I realized I had a CEL. The coolant was from a tiny, hairline crack on the top of my radiator that I have since covered with some "Quicksteel" putty (temporarily). There is still a tiny leak coming from there that I need to take care of. The CEL is "Insufficient coolant temp to enter closed loop fuel control," and I just now realized that the pinhole leak is leaking directly onto my o2 sensor connections (butt connected wires). While I was in my car earlier I had checked to see if my o2 sensor was cycling, and it was. When I got home, however, my o2 sensor was not cycling. I'm fairly certain the coolant leak onto the o2 sensor wires is causing issues, but would I be correct in assuming the malfunctioning o2 sensor could be preventing me from entering closed loop fuel control? I don't feel like changing out any temp sensors or my thermostat unnecessarily. Also, does anyone think this could cause any long term issues with my o2 sensor?

 

[sag1441]

yes a bad o2 sensor will lead to poor fuel economy

 

[hereitcomes]

A bad o2 sensor will definately lower performance and gas mileage. A coolant leak on the other hand not so much. Oil leaks would be more prone to poor gas mileage, and low oil pressure.

 

[Cool Mr Steve]

I get the feeling you guys didn't read my post I know that a bad o2 sensor could lead to poor fuel economy, I was curious if it could prevent my car from entering closed loop fuel control. I explained the coolant leak because it was leaking on my o2 sensor wiring, not because I thought losing coolant would be detrimental to my mileage. Thanks for the replies, though.

 

[absolute_DSM]

and I just now realized that the pinhole leak is leaking directly onto my o2 sensor connections (butt connected wires).

If your using butt connectors on your O2 sensor and they have coolant on it, youre gonna have a bad time.





The ECU must see a cycling O2 sensor to go into closed loop.

 

[Cool Mr Steve]

Ok, I cut off the old connections and put on some new connectors and wrapped them up really nice. The o2 sensor was cycling and happy. Now, I've been driving it for about 2 1/2 hours and my CEL came on again. Same code, the "insufficient coolant temp to enter closed loop" and I checked my o2 sensor and the damn thing doesn't show any voltage. While I'm driving and I put my foot heavily into the gas for a few seconds, it shows some minor signs of life. I would assume the sensor is bad, but it would kill me to change it and that not be the problem. This whole issue started when I had coolant leaking directly onto the o2 sensor wiring, so it leads me to believe that it should be a problem with the wiring. Is there any other way to test the o2?

 

[wvturbo2]

IF it was leaking on the wiring odds are its messed up the o2 sensor not the wiring. Fix the leak then change the o2 so that it will not leak on the sensor again.
You could check fuses to see if you by chance blew a fuse.

 

[absolute_DSM]

If you have a logger and its not cycling, it is bad. Replace it with a OEM type that doesnt require and splicing of wires. Those ones tend to cause problems. I know its more expensive but think of it like this. Replace a $50 sensor 2 times in 6 months or just get a nice $100 one once in 6 months. Your choice.