My Dakota rt is throwing codes for high voltage in the o2 sensors. The guy before me put a custom exhaust on, and there are 2 o2 sensors (one per bank) right below the exhaust manifold. There is also one after the pipes meet into a single exhaust. I found an open plug for an o2 sensor, but there is nowhere on the pipe to put an o2 sensor. There is no cat on the exhaust ether. I just want the engine light turned off and for the truck to work correctly and efficently (it runs extremely rich right now). Any ideas as to where the 4th o2 sensor might go. I'm open to all and any ideas

 

There should be 2 cats, one for the left bank, and one for the right bank. And 2 upstream O2 sensors, and 2 downstream O2 sensors after the cats. The upstream O2 sensors tell the ecm what the A/F mix is, and the downstream sensors tell the ecm if the cats are working correctly........ I've heard you can just plug in the rear sensors and tie them up in clean air and the cel will not come on............ Personally I haven't done it so I can't say if it works, worth a try I suppose it should turn off the cel, but the upstream sensors control the fuel air mixture.

 

Ok, I'll try plugging in an o2 sensor into it. I think the guy before me just took 1 of the downstream o2 sensors and put that in a s just let the other one dangle thinking it world work. What an idiot

 

Rebel is mostly right. However, there are 2 different exhaust configurations depending on year.

The early (00-) trucks came with one cat and 3 oxygen sensors for 49 state trucks, and three cats and 4 sensors for California trucks.

On the 49-state trucks, there was one O2 off each manifold, and a single after the main cat (after the wye).
On the California trucks, there was an O2 off each exhaust manifold, then a mini-cat, then another O2, then the wye, then the main cat (but no further O2 sensors).
On either setup, you could delete the cat(s) and ziptie the downstream O2 sensor(s) to the frame rail and the PCM would be happy.

01+ trucks were all produced with the California emissions. The O2 calibration was also modified to recognize when the downstreams were in "too clean" of air. As a result, zip-tieing the downtream sensors is a 50/50 shot depending upon your climate. If you live in a horrible SMOGgy place like LA, it might work. If you're in the middle of BFE, it will probably yield a light.

and yes, a high voltage error usually means it is unplugged. Trace back the existing downstream and see if it comes off the left or right side of the transmission tunnel. Right would be 2/2, left would be 1/2 I believe.

 

It's a 98 model, but I dont think it's a California truck, but on the other hand it does have 4 sensor ports. So if reading correctly as long as I get an 02 sensor and zip tie it to the frame itll work? Or do I need to make something to mount a sensor in the pipe?

 

It's a 50/50 shot tieing it up. They make Weld in bungs for O2 sensor ports if you want to go that route. I'd try tieing it up first, because I'm sure if you put it back in the pipe is going to throw a cat converter code. You could get O2 sensor simulators........ They fool the ecm into thinking the cats are good, in reality there isn't any lol. I don't know what they look like, and I don't know what they cost.

 

[QUOTE=01+ trucks were all produced with the California emissions. The O2 calibration was also modified to recognize when the downstreams were in "too clean" of air. As a result, zip-tieing the downtream sensors is a 50/50 shot depending upon your climate. If you live in a horrible SMOGgy place like LA, it might work. If you're in the middle of BFE, it will probably yield a light.=QUOTE]

I was wondering if they could detect clean air from being outside the pipe.

 

I've seen people use spark plug defoulers to fool the ecm. I think it's easier to deal with a cat code than a high voltage code

 

O2 simulators do not work on the JTEC platform, not sure why. Been tried many times by people.

De-foulers do work, but tying to frame rail should do the trick.