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O2 sensor ground?

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Old Sep 10, 2020
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O2 sensor ground?

I have a 2003 Civic EX VTEC
In my car Fuse 4 says it's (20A) Rear electric window – LH. It rides the top of the fuse box.
When I look at the diagram Fuse 19 says (10A) Anti-lock brake system (ABS)-with ESP, alternator, cruise control, evaporation mission(EVAP) canister purge valve, heated oxygen sensors (HO2S), vehicle speed sensor (VSS).
My Power check from the vehicle side to ground is there, the Black with Orange wire.
The Ground check reads 0 volts from the Black with White to positive side of battery.
I don't think the fuse is bad because my cruise control still works but I'll check it out tomorrow.
I hope the wire didn't break from the connector to the ECU. I hate getting under there.
Also I have the lovely VTEC code P1259. Joy.
Wish me luck. this my only ride because my Nissan lost time so I have to replace the engine. Sheesh. I'm too old for this stuff.

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Sep 11, 2020
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Re: O2 sensor ground?

Well, after a TON of digging, I found that the heater resistance is supposed to be 10 to 40 ohms (I dug really deep into this thread).
I checked the downstream O2 sensor heater resistance and it was 3.5 ohms. This was my code P0141.
I checked my upstream heater resistance and it was 15,5.
Hmm.
Well, I had a wonderfully brilliant idea. Let's swap them and see what happens.......
LOW and Freakin BEHOLD!!!!! I pulled a P0135 code. B01S01 Heater Malfunction.
I was like, I guess it's the sensor and not the car.
I called the parts store and asked for an upstream sensor. $XX.XX.
I checked it's resistance and it was 3.5 ohms.......
I asked for a downstream sensor and checked it. The heater read 18.8 ohms.......
I bought the downstream sensor and put it into the upstream spot and viola. CEL go away.
Noe my VTEC code was because I was low on oil.

The new sensor was a Denso and it was not correct.
The heater resistance HAS to be between 10 and 40 ohms.
The brand-new Denso upstream read 3.5 ohms.
I've never heard of that.

Word to the wise, take a meter with you as was said earlier. It worked for me.
I have to do the drive cycle and get an E-Check.

Wish me luck.
Old Sep 10, 2020
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Re: P0141 Ground Issue

"Much of the ECM controlled switching is accomplished by turning grounds on and off. "

can you tap into this ground line and just attach it to ground so the ECU reads the ground?
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Old Sep 11, 2020
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Re: O2 sensor ground?

The Ground check reads 0 volts
The pcm only provides ground when it wants the sensor to heat up, and as soon as it determines a problem it disables that ground for the sensor and sets the fault code..

You clear the code like usual and then start the engine........ the check engine light turns on about 5 seconds after you start the engine, yes?
That means as soon as the engine starts you've only got 5 seconds to check for ground for that sensor.
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Old Sep 11, 2020
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Re: O2 sensor ground?

You're right. after code is cleared, 5 seconds and CEL comes on. I'll check in a bit.
It's comfortably cool outside but I'm like a lizard and have to warm up before I can move.
I'll keep you posted this afternoon
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Old Sep 11, 2020
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Re: O2 sensor ground?

Well, after a TON of digging, I found that the heater resistance is supposed to be 10 to 40 ohms (I dug really deep into this thread).
I checked the downstream O2 sensor heater resistance and it was 3.5 ohms. This was my code P0141.
I checked my upstream heater resistance and it was 15,5.
Hmm.
Well, I had a wonderfully brilliant idea. Let's swap them and see what happens.......
LOW and Freakin BEHOLD!!!!! I pulled a P0135 code. B01S01 Heater Malfunction.
I was like, I guess it's the sensor and not the car.
I called the parts store and asked for an upstream sensor. $XX.XX.
I checked it's resistance and it was 3.5 ohms.......
I asked for a downstream sensor and checked it. The heater read 18.8 ohms.......
I bought the downstream sensor and put it into the upstream spot and viola. CEL go away.
Noe my VTEC code was because I was low on oil.

The new sensor was a Denso and it was not correct.
The heater resistance HAS to be between 10 and 40 ohms.
The brand-new Denso upstream read 3.5 ohms.
I've never heard of that.

Word to the wise, take a meter with you as was said earlier. It worked for me.
I have to do the drive cycle and get an E-Check.

Wish me luck.
Reply
Old Sep 13, 2020
  #6  
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Re: O2 sensor ground?

Passed E-Check. doing good and now have plates for it.
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