Question on 173 code

[BIGSHOMIKE]

I have been getting a CE light in the AM only when it's like 30 outside, as soon as the temp gauge moves it goes away. I pulled the code and got a 173, I know the sensors are fairly new so I was wondering if it could just be the cold? I pulled the sensor to see if it was gunked up from running rich for so long but it looked ok. I never get the light exept when it's really cold outside, even if the car is cold.

Thanks

 

[BIGSHOMIKE]

What I mean is the computer richens up the mix when it's cold, so would this set the sensor off? I didnt find too much on this doing a search. It doesn't give the 172 code with the 173, and it's not affecting driveability or mileage at all.

Thanks

 

[rangerj]

BSMIKE,

As the engine runs the computer constantly adjusts the fuel input to keep the mixture at the optimum 14.7 to 1 ratio. The computer gets this mixture information from the oxygen sensors.

The oxygen sensors "switch" from rich to lean, and back, continuously. The code 172 indicates a lack of oxygen sensor switches to the rich side. In other words the sensor is indicating a lean mixture.

When the engine and all its parts are cold, everything is contracted. Once the engine starts to get warmed up, things start to expand or swell.

I advance the theary that you have a vacuum leak, such as a cracked vacuum hose, or a gasket problem, that is sucking in air when the engine is cold, and sealing up(to a degree) once the engine gets warm (or hot).

The code does not mean that the sensor is bad. It means that the sensor is sending the computer some bad news about the air/fuel mixture. If the code was a 173, it would indicate a rich mixture.

Look for a vacuum leak or some other source of unregulated air getting into the engine. A cut or break in the rubber snorkle to the throttle body can also be a possible cause.

Look for anything else that might be causing a lean condition when the engine is cold! rangerj shrug

 

[rangerj]

Mike,

I don't know why I locked on to the 172 code when you asked about a 173 code, DAH. shrug

The 173 codeis the "rich" side of the equasion. The system is intended to be a little rich when it is cold, but to throw the code would indicate to me that the mixture is too rich.

I would think along the lines of; is the air filter clean, is the IAB working properly or does it need cleaned, does the MAF need cleaned, are any injectors leaking, is the fuel being regulated properly, etc?

You say everything is runniong very well, good fuel economy, performance, etc. Well, leave it alone. If the CE light goes out once the car warms up. I would not worry about the 173 code.

If it was a 172 code, that is a lean mixture, I would be worried. But a rich side code, hey, let the EPA worry about it!

If you start to have drivability problems, or "symptoms", then get into it.
rangerj thumbs_u

 

[BIGSHOMIKE]

Ya it goes away really quick, and doesn't even come on till you start driving (never at idle I mean). This morning I had to shovel some snow so it warmed up longer than usual and it never came on. Thanks for the info.