Ok I swapped out a D16y8 that has a blown head gasket that I just didn't want to deal with as I had a 98 LX D16y7 with just over 97,000 on it and I figured hell I knew I was keeping that motor for something and the ex fell in my lap. Now I knew that I would have to swap harnesses as the 98 wiring harness won't work with the 99, so I hunted down a 2000 LX manual wiring harness and ecm installed them car runs like new. Problem, O2 Sensors were shot and the exhaust manifold had a copy of the Grand Canyon running through it. So new O2 sensors (Bosch cause that is what they had available at the local stupid store) and a new EX Manifold with CAT, put it all in and bam codes cleared and I started driving it to get the monitors to key up as I live in CA and the TailPipe Natiz's have to get their pound of flesh. But damn me if I can't get the car to drop this PO136. Now I am desperate after a month of buying Denso Sensors and then in desperation Kiwksen Sensors, my fuel trims look perfect but the damn value of the the B1S2 O2 sensor will not drop below 1.275 mil amps. Anyone with a bigger brain that I ever run into this. My kid got a job merching at 7up and he needs this thing smogged, Can Any ONE HELP

 

Did you bother to see what the code meant? Or did you just keep on tossing parts at it?

 

low voltage bank 1 sensor 2 or post cat sensor has low voltage

 

Where is the secondary O2 sensor plugged in Fastopel ??? I suspect your problem is in the integration... you have stated that you are using a '00 Y7 engine harness which places the primary and secondary O2 sensor plugs on the front of the engine near the area where the block meets the transmission since the cat is essentially the exhaust manifold and the sensors are placed before and after the cat cylinder right up front. Your chassis is an EX, which places the cat cylinder under the chassis aft of the rear k-member and the secondary O2 sensor plugs into the chassis harness behind the shifter in the center tunnel... the EX engine harness only has a primary O2 sensor plug up front to meet the O2 sensor found in the top half of the exhaust manifold.

Contrary to the suggestions by others on this site, I always suggest using the engine harness found in the chassis as it was delivered from the factory and modify it to fit the engine you wish to swap in. This guarantees the proper integration for the sensors and circuit pathways that you simply don't think about. Obviously, the "K" and "J" series swaps are exceptions, but for "B", "D", "F" and "H" series engines... do what I suggest. Your life will be easier.

 

Thank You JRCivic1, I appreciate your insight and help. That was the answer I was looking for, Alas, I would have used the original wiring harness but the previous owner did some serious modification to the original harness and I could not make heads or tails of what was done. Or why for that matter. I did realize that the 00 Y7 harness was going to come with its own unique challenges and it wouldn't be as easy as 123. I suspect that a obd1 harness had be installed and chopped to match. I have found that the only thing worse than an ******* with a black can of spray paint and a new set of wheels is an even bigger ******* with the internet and a pair of wire cutters. As everything was chopped up I had no idea where the original connectors. I am a European Car Guy for the most part, though I cut my teeth early on a 78 CVCC and I must admit, I miss that car daily. I did realize that there was no sensor input early on, but I jumped the white/red wire coming in on the green plug under the glove box, to pin 23 on the ecm but this gave no result. I suspect that the signal lead to the ecm on the 00y7 engine has a short which was further compicating the problem. Thanks Again.

 

Cuz you need to make sure you need to make the rest of the connections to the secondary 02.

problem with NOT using the harness that was meant for the car is that you have to hunt down and make the connection for any missing. It sounded simple when you get the correct engine harness for the engine you're putting in but when it comes time to troubleshoot are you capable of following diagrams, cross reference it with YOUR custom work and resolving the CEL.

your issue is that your original secondary o2 plug is still connected, you need to either depin and add in the new run or use the original o2 plug and verify it's getting signal to the ecu and just extend or buy and extended wire harness.

 

It should be noted that fuel trim is done only from the first sensor.

The second sensor is there merely to check if the cat is doing something. It doesn't affect the engine at all other than throwing a P0420 code if it doesn't like what it is seeing. But of course you need it all hooked up and working to pass a smog check.

 

Inspections.... such a painful thing....