Correct call?
Data pid for the O2 showed it to be sluggish and looking like a dead sensor. However, the heater pid was not toggling back and forth from on to off. The front AF sensor heater was toggling, but not the rear.
I decided to scope the heaters on both and I found good 12v into both, but the ground on the rear o2 was not being pulsed.
This capture is orange representing the ground on the AF heater and green represents ground on rear o2 heater.
AF is probed sensor side, O2 is probed at ecu pin.
My only question here is why didn't I get a heater circuit code, instead of/in addition to the high signal code? Am I making the right call? That voltage spike resonating into the AF side of things tells me this car needs an ecu and an O2 to be safe.
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The voltage spike you are seeing is, most likely, Secondary Ignition feedback. The closer your test leads are to a coil/plug wire, the more you will see this.
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"Understanding a question is half an answer."
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And yes, that green trace is backprobing the ecm underhood.. The square wave is the healthy AF heater ground, backprobed sensor side just for comparison. The green O2 heater ground is the same spiky 12v on any point on both heater wires.
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Deltron wrote: AF is probed sensor side, O2 is probed at ecu pin.
I see, now, you DID test at the ECU. I missed that. That makes me agree with you on the heater driver.
"Knowledge is a weapon. Arm yourself, well, before going to do battle."
"Understanding a question is half an answer."
I have learned more by being wrong, than I have by being right.
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"Knowledge is a weapon. Arm yourself, well, before going to do battle."
"Understanding a question is half an answer."
I have learned more by being wrong, than I have by being right.
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"Knowledge is a weapon. Arm yourself, well, before going to do battle."
"Understanding a question is half an answer."
I have learned more by being wrong, than I have by being right.
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I'm using custom Aes wires on a maxiscope for that capture, also the same pattern I got on my uscope while in the air
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Deltron wrote: If I use a test light to ground, I'll just turn the heater on. I've seen Paul do that in videos.
That is correct....IF the wire is good and that is NOT a bias voltage you are seeing. But, IF the wire is broken, and that is NOT voltage coming through the heater, but a bias voltage coming from the computer, the voltage will disappear and the heater will NOT turn on.
"Knowledge is a weapon. Arm yourself, well, before going to do battle."
"Understanding a question is half an answer."
I have learned more by being wrong, than I have by being right.
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"Knowledge is a weapon. Arm yourself, well, before going to do battle."
"Understanding a question is half an answer."
I have learned more by being wrong, than I have by being right.
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Deltron wrote: Ah, yes. Indeed. SO I could unplug the sensor and look for the voltage with a multimeter or use a test light and check the data pid. Those are my 2 options to rule out bias.
Yes.
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"Understanding a question is half an answer."
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There are 1000 ms in 1 second. 60 seconds in one minute. 60000ms in one minute.
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Has anyone searched for TSB's on this code yet? I recall going down this path on a similar Mazda, and found a TSB that recommended cleaning the throttle body. :silly: Apparently, the carbon in the throttle body would 'hold on' to fuel, which would then get sucked into the engine during fuel cut decel. The PCM's looking for the downstream O2 to peg lean during fuel cut, so it'd get upset when the downstream O2 would suddenly go rich.
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Tyler wrote: Little late to the party. :blush:
Better late, than never.
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"Understanding a question is half an answer."
I have learned more by being wrong, than I have by being right.
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Sometimes I hate being at a dealer. I often have interesting things ripped away and auctioned.
Thanks for the help guys.
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