Thread: O2 sensor error

What are the exact codes you are getting?

The codes don't really mean that the sensor is bad and should normally always read correctly with a scanner and show no signs of bad mpg or sluggish performance.

They are just saying that the computer is not seeing the correct amount of switches lean and rich of stoich (450-550mv) in a given amount of time. Say it needs to see 90 switches in the 60 second test but only saw 80, it then sets the code are 2 failed times. It's a pretty common problem with header installs because the o2 sensor placement is now different but I haven't seen much of this problem on stock exhaust.

I only use AC delco/denso sensors too, I feel that bosch sensor end up giving people problems.

Yes and no but mainly no.

The sensor itself is working just fine but just in the first test the car does for the o2 sensors (it only does the test once per drive cycle I believe) it didn't switch enough times. It's possible the new sensor isn't working correctly at that given point. If you can warranty the sensor, do so and see what happens.

A poor electrical connection or a long shot being that you have a small vacuum leak going on.

The scanner would be able to show you the fuel trims, anything positive or above 6-10% all the time if a possible vacuum leak. Bad leaks will show +16.4 all the time.

being you have a 02 and no cat i believe, you said silencer? wrong terminology for what ever part you mean. will set the rear o2 code, as its failing the cat test and over fueling and that might be burning up your o2 sensors.

heater element's go bad, replace the sensor, use only delco sensors, no idea what brand you used but aftermarkets are not always so good and can fail or not work right.

if you have no cat you can try a simulator thing, or a pair of bungs to pull the o2 out of the pipe to trick it to read right.