O2 Extension wires bad?

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O2 Extension wires bad?

Postby AndrewS015 » Mon Feb 29, 2016 2:47 pm

So I have had a PPE long tube header installed for a couple years. The rear O2 extension wire was too long for how I routed it, so I had it loosely coiled and zip tied to the bracing until recently. I kept getting the occasional P0131 code every few months, and the exhaust would rattle at idle.

Anyway, I recently adjusted the exhaust to stop it rattling. I checked the O2 sensors, and the front one was loose, so I tightened it. I rerouted the rear extension wire to go to the other side of the car, over the transmission, zip tied to the brake lines. If I understand the installation instructions here correctly, that is how it is recommended to be run. I thought the wires looked good, undamaged and not pinched. Connectors looked good and were connected solid.

But now I get immediate CEL when I drive the car. I get P0131, P0139, and P2096. If I clear them, they come right back the next time I drive.

Could the extension wires be bad? Is there a way to check? Should I replace the front O2 sensor since it was loose and is the most likely part to be damaged?

I am getting codes for both O2 sensors, so I'm not sure what to look at first. Replacing both sensors and extension wires would cost a few hundred dollars. It is also not fun working underneath the car, so I hate to keep trying things over and over.
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Re: O2 Extension wires bad?

Postby Brian » Mon Feb 29, 2016 6:30 pm

Sounds like missing connection indeed. Grab a multimeter and check continuity from pin in one plug to pin in plug at the other end. Before you even do that LOOK into the plugs at the pins, did they get yanked out of position too far back inside the plug to make contact?
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Re: O2 Extension wires bad?

Postby AndrewS015 » Tue Mar 01, 2016 12:13 pm

Thanks for the quick reply. I'll have to look at the pins next time. If they look OK, I will take the wires out and continuity check each one.
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Re: O2 Extension wires bad?

Postby JohnL074 » Sun Mar 06, 2016 3:26 pm

I hear frequently when people extend ecu wires that they start running into codes. Would installing a couple of ferrite beads on the wires clean up the signal that's being lost?
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Re: O2 Extension wires bad?

Postby Brian » Sun Mar 06, 2016 5:12 pm

Indeed lots of issues when customers chop and extend the wires, but my assumption from the first post was this customer is using our optional extension cables that make the install plug and play.
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Re: O2 Extension wires bad?

Postby morrisg » Sun Mar 06, 2016 8:55 pm

JohnL074 wrote:I hear frequently when people extend ecu wires that they start running into codes. Would installing a couple of ferrite beads on the wires clean up the signal that's being lost?


Ferrite beads are used to knock down high frequency noise in the signal. Since the oxygen sensor is the only thing that is down there, it isn't likely that it's getting any noise injected into the wires at the sensor. If you want to try some ferrite beads, then I'd try back at the ECU after the wire has run all the way back. That might take care of any interference from other wiring in the engine compartment.

IF high frequency noise on the sensor wiring is your problem, then a ferrite bead back at the ECU will help. But that's a big IF.
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Re: O2 Extension wires bad?

Postby AndrewS015 » Tue Mar 22, 2016 10:36 am

I just wanted to give everyone an update. I checked all the wires, the pins were all good, continuity was all good.

I bought a new front O2 sensor and all the codes went away. I even bought the sensor for an NC1 because the NC2 sensor was twice the price and everything works great. The only difference in the sensors I could see was the cup around the hex on the sensor was different.
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