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I have noticed a little white cloud behind my car, on which I recently installed a 2.2 with ~90K miles. I blamed it on the cold weather, but while waiting at a red light this week I realized most other cars were not producing anything similar :banghead:

 

Today (very cold) I asked my wife to start the car while I played close attention to the exhaust. When she started the engine, there wasn't any significant amount of white smoke. Then I asked her to bring the engine to 3K RPM, and then I saw the smoke coming out. It didn't smell like coolant at all (no sweet smell or anything like that), but rather like gas... lots of it.

 

The EJ22 came from a car that was totaled several years ago so I don't know much about it's history. My question is: can the excess fuel create this white cloud somehow, or should I assume a head gasket is blown? How can I diagnose this?

 

BTW: the check engine light is on, with a code about the oxygen sensor circuit being bad, so I assume this is the cause of the excess fuel. Is it a fair assumption?

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That's the weird part: the code is for a "bad O2 sensor circuit", not for a bad O2 sensor. From what I have found, this means the sensor's heater is not working as it's supposed to, but the O2 sensor is producing a "legal" output. This seems to be backed by the fact the gas mileage is not particularly bad -I think-. I'm more concerned with the catalytic converter melting or something like that...

 

Now back to our normal programming: white smoke :(

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That's the weird part: the code is for a "bad O2 sensor circuit", not for a bad O2 sensor. From what I have found, this means the sensor's heater is not working as it's supposed to, but the O2 sensor is producing a "legal" output. This seems to be backed by the fact the gas mileage is not particularly bad -I think-. I'm more concerned with the catalytic converter melting or something like that...

 

Now back to our normal programming: white smoke :(

 

I got the same code, circuit error, when the O2 sensor had snapped in half due to driving over a huge snow mound. Replaced with new OE sensor and all is lovely now.

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Are you certain that it isn't just condensation/fog that you're seeing? Not all other vehicles will have the same amount in their exhaust depending on the temperature of their particular exhaust components at that particular time. Smoke will hang in the air and diffuse by dilution, regular exhaust condensation will dissapate when the cloud of condensation equalizes with the temperature of the surrounding air at the dew point. If you have smoke coming out of your exhaust, it will happen regardless of the outdoor temperature.

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To add:

Let the car idle a few minutes to warm it up. Makes it easier.

If the cat is very old as a precaution I would hold the bung with one wrench while turning the O2 with another. I have had an O2 bung rip completely out while trying to remove the sensor!

Bosch(the originators of O2 sensors) are a good replacement,also.

 

O.

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