blackmaxx96

iTrader: (23)

Ok so I think I may have finally figured out what's going on.
Just this afternoon the car got alot worse and now it's throwing 05-03 and 03-03 along with 09-01 and 10-01.

All four codes refer to the front and rear O2 sensors (which are brand new)

I've looked at the harness, connectors and they seem fine.
There's no reason that both o2 sensors would go bad.
It's some pertaining to the actual o2 circuit.

Could it be that the main fuse block on the drivers side by your knee is bad?
I've replaced it once because it shorted out... but that was over a year ago.

The only thing I could think is that where the 15 amp fuse for o2 sensor is bad.


All four codes say it's either the sensor unit, or harness/connector.
I've replaced the o2 sensors twice now with Bosche OEM plug and plays.
It says if sensor checks out good it's harness/connector.... Does that mean the entire wiring harness?

Any help will be appriciated

blackmaxx96

iTrader: (23)

Also, something I just remembered is that I don't have the rear o2 sensor in.
Hasn't been in for about a year and a half now.
Code 0707.
It says it's not an actual sensor, it's only a two plug.

But I ran with that out for about 5 or 6 months before this problem even started to occur.

Maxima880

When the manual refers to the wiring harness, it's refering to the wires that make up that particular circuit. In the case of the O2 sensors that's two wires that run between the ECM and the sensor, a hot to the sensor, and a shield ground to one of the two that run between the ECM and sensor. You're gonna need a multimeter, access to a manual, and patience to systematically test for voltage and continunity between certain terminals. If you don't have these things it's nearly impossible to trace down a wiring problem without replacing parts that aren't broken. Have you confirmed that you have voltage to the sensors yet?

blackmaxx96

iTrader: (23)

The only problem I see is that those wires are integrated into the main harness...
Wouldnt I have to cut open the harness to expose those wires???

I'm thinking i'm going to bite the bullet and take it to a shop finally...
I'm not getting over 15 MPG now...

Mike



******

Maxima880

Yea, without O2 data to the computer I imagine you'll see performance loss and gas mileage drop. You don't cut wiring to test circuits. You test between connectors. For instance you might unplug the front sensor up by the radiator and the main harness into the computer and test for continuity between those points. If continuity exists then you know that part of the circuit is intact and you move to the next part of the circuit. You can verify power to the sensors with a simple 12v circuit tester. That would be a place to start since your having trouble with both it could be due to no power from the ignition.

blackmaxx96

iTrader: (23)

Hmmm very true...
I'm just afraid that there is a short somewhere in the actual wiring harness.
I have a mechanic that I take all my stuff to if I don't attempt it myself.
One thing he is very good at is electrical stuff....
I honestly just hate dealing with it, and it's worthwhile to me for him to just fix it for me and know that it's done exactly right.
I will definitely shoot him this information though just to give him a heads up so he knows what to search for.

Thanks for all your help!

Mike

urmab

iTrader: (7)

Maybe you should try a different ecu and see if the problem persists. I know when I switched from a 98 ecu to a 95 I had the rear o2 sensor code. And it was that the wire pin out was different on pre 96 years. I'm not sure that this is going to help but I say try a different ecu

Maxima880

I understand. Electrical problems can be the most frustrating. Often difficult to isolate the problem and difficult to fix. One thing I've learned in many years of working on my cars is my limitations. For instance I still won't go deep into an engine – too many parts to keep track of and a lot of knowledge needed to reassemble correctly. Good luck with your car.