O2 Sensor Failure in 05' Honda Civic Automatic
 

My O2 sensor in my 2005 Honda Civic has failed (the light ironically/disturbingly came on immediately after I left from getting an oil change from my normal mechanic).

I checked prices online for this part and it seems reasonable, but then was quoted in the $500-600 range by my mechanic to get it replaced. I called another mechanic to get a quote who asked me which O2 sensor it was. Ignorant as I am I didn't realize there were multiple O2 sensors but I guess it's the expensive end of the options because he checked in his database for my car to see that they were up to +$400 so I guess my mechanic wasn't far off.

I assume this isn't something easily fixable for an unfamiliar and unconfident DIY guy like myself?

The car is pretty old with +200K miles on it and other service recommendations are beginning to pile up; I might just be tempted to look at the new Civics at this point.

There are two sensors. There is one before the catalytic converter and one after. The most challenging part of the DIY would be to remove the old sensor as you will likely be battling years of corrosion. However, a $500-$600 quote is likely for a catalytic converter replacement. At over 200,000 miles, it is likely the converter is restricting flow or has lost its catalytic capabilities. You can replace the sensor in your garage, but if the converter needs to be replaced then the engine light will return.

Hope this helps!

Thanks for the response!

The code was "po135" though and it was specifically cited as being that the O2 sensor has gone bad. I guess the "po135" code doesn't specify or indicate which of the multiple O2 sensors needs to be replaced, does it?

(Just wanted to quote you in case that matters).

Anyway I talked to a couple of other mechanics in my town and they all quoted around the same price. No idea why it's so expensive when online it looks much more affordable.

The code po135 is given when the heating elements in the O2 sensor are no longer working. The O2 sensor is still properly functioning, but not as efficiently. It is difficult to say whether it is the upstream sensor or downstream sensor, but perhaps a mechanic could tell you that in a diagnosis. The mechanics are quoting you for the labor. They will diagnose the problem and rule out any other possible causes (such as wiring). A reasonable quote is $200-$400 given the sensors are normally in hard to reach places and sometimes require special tools to remove them. In this case, one sensor is located just under the exhaust manifold and one sensor is after the catalytic converter. The sensor is around $100 depending on which brand you select. I believe Denso is OEM. If you plan to replace it yourself, you will need to jack the car up to access the exhaust system. In addition, unless you plan on cutting the wires and using a deep socket to remove the sensor, you will need a special tool to remove the sensor without cutting the wires.

Thanks, AS. I feel better about going through with it now with a better understanding of the reasoning behind the rate.