I have a 1994 Toyota Pickup 4WD Regular Cab with the 22RE motor that has an exhaust header without an Oxygen Sensor port on it and my cat has been removed. I am getting an OBD Code 25 causing my check engine light to come on. Is the code 25 related to not having the O2 port in the header?

Thanks in advance for your help.

 

Well, what does Code 25 mean?

"Heated oxygen sensor output is less than 0.45 V for at least 90 sacs. when heated oxygen sensor is warmed up" http://web.archive.org/web/201211190...85diagnosi.pdf

So yes, your computer is telling you "Where the heck is the O2 sensor?"

By the way, without a sensor, you'll be running in open loop mode all the time. Terrible gas mileage, and very poor performance. Not to mention a shoot-stack of pollution.

 

I have a single O2 Sensor, it is just about 1.5 feet from the manifold.

 

Single wire oxygen sensors are not self heating, and rely on the hot exhaust to heat the oxygen sensor for proper operation. If a single wire oxygen sensor is not getting hot enough ( is too far from the heat source; engine) it will not work properly.

I don't know if that is your problem, but it is a possibility.

Also, I thought 1994 Trucks had 4wire heated oxygen sensors. Is this true?