Hi All,

I read the other day in an automotive repair book that O2 sensors need to be replaced every 30,000 miles, and that old O2 sensors can effect mpg and overall engine performance (i.e., just like old spark plugs).

Do you all think this is correct in your opinion? Is it worth the time and expense to change these? I don't think my post cat O2 sensors have ever been changed...

Any tips are welcomed. Thank you.

 

lex
the 02 sensor works or don't work you answered your own question

 

My O2 sensors do indeed work. However, just like degraged spark plug reducing MPG and performance, would an old O2 sensor also reduce gas mileage and power...

For example, imagine if you left your spark plugs in for 12 years...

 

lex
I changed my plugs at 73,000 and they looked new. 02 sensors work or don't

 

When we sold our SC400 at 334K miles, it had the original O2 sensors and they worked as well as the day the car was new. The mileage improved slightly over the years as did engine performance.

 

Are you sure the "automotive book" you read was not an older edition (or an automotive industry book)? In the earlier days, O2 sensors didn't last any longer than spark plugs. Back them, plugs had to be replaced every 20-30K miles...now they last AT LEAST 100K miles. Newer materials and technology makes them last far longer than they used to.

Like others have said - O2 sensors either work, or they don't....there's nothing in them that really degrades over time. The usual failure is internal shorting or a wire melting due to the case cracking - the O2 element itself is practically indestructible.

The tip of the sensor itself (the part that sits in the exhaust pipe) can get sooty or dirty if your air/fuel ratio is not correct (dirty MAF sensor, or running too rich), but if you run decent gas, and run some fuel injector cleaner (or Seafoam) in a tankful of gas once in a while, that shouldn't be a problem.