Just curious to know if there is a way for me to find out if I have a 3 or 4 wire o2 sensor in bank 0 without having to get under there and remove it?


1998 Blazer

 

It's a 4.

 

Definitely a 4 wire O2 sensor... Why do you ask? If it is to get a universal, cut and splice in sensor, save your money for a genuine AC Delco! You, your wallet (in the long run) and your truck will be much happier.

 

Sounds like good advice. thanks for the answer.

 

Ive looked at a few auto parts sites to order the O2 sensor and they all say the same thing.

O.E. type
4 wire; heated; 2 required.
Does this mean I need to replace both sensors at the same time?

 

Unless you are doing a general tune up and wanted to replace the O2 sensors, you should not have to replace them both. I generally never recommend changing an O2 sensor until it has been properly identified as being lazy (slow response to changes in injector pulse width) or defective through slow warm up or some other defect (no response, etc). And even then, I would switch the O2 sensor side to side and try to replicate the problem on the other side of the motor to rule out a fuel supply issue, exhaust leak, or a wiring problem.

The reference you speak of with the "2 required" simply means that there are two of this particular PN used on the vehicle. You always want to use the OE type which means that it will plug straight in to the wiring connection on the vehicle. The universal types require you to cut off the wiring connector from the old sensor and splice it onto the new "universal" sensor. The problem with this is that all O2 sensors "breathe" through the wires. The air that is pulled through the wires is used to compare O2 content with that of the exhaust. That is the basics on how the O2 sensor works, via comparison. By cutting and splicing, you may inadvertently restrict the flow of air to the O2 sensor, causing it read incorrectly. This is also the reason to NEVER use any dielectric grease on an O2 sensor connection.

 

Got it. My Check Engine light came on and I noticed my MPG is bad. I hooked up a code scanner and the only trouble code I saw was pointing to a bad o2 sensor.

Thanks Again.

 

I would start by replacing just the sensor which was indicated by the code. What was the specific code that was returned?

 

I do not have the scanner in front of me but from what I can remember it told me which bank needed replaced. I can look when I go home in about 30 minutes.

 

currently have the same problem, Bank1 below efficiency threshold or something, which oxygen sensor would you replace first..the one before the cat or after....