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oxygen sensor heating cycle smog readiness question

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Old Aug 25, 2016 | 07:34 PM
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Default oxygen sensor heating cycle smog readiness question

will my 02 heater cycle become ready with the downstream swapped with the upstream? swapping the 2 & just wiping off the carbon buildup stopped bad idle & ses light - but from what i've read the 02's are the same piece in both functionality & construction & that the only difference was length & that the downstreams are HEATED - so, with my downstreams currently being upstream (non-heated upstream in the downstream), is that causing the 02 heating cycle (smog readiness) to not finish?
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Old Aug 25, 2016 | 10:29 PM
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What system are you using? All modern ecu's use 4 heated O2 sensors .They compare up and down stream voltages to see if there is a problem with the cat. Steve
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Old Aug 26, 2016 | 02:22 AM
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well, apparently our 98-02 firebirds & camaros (at least v-8's) use 2 non-heated sensors pre-cat & 2 heated post cat - research it it's very easy to confirm this info (not being a smart *** - i too was unaware) -- and have figured out since posting this earlier that running a non-heated sensor post-cat will NEVER allow the sensor heater emissions ready cycle to complete. ordered new ac delco 02's just a bit ago - just got all 4 since they were really cheap & the old ones ARE bosch (am guessing previous owner replaced at some point) & are shot looking - they all 4 literally look like spark plugs with 150k+ miles on them.
... so, hopefully this post may help someone in the future - the oxygen sensor heater cycle will NOT become ready without a non-heated 02 sensor post-cat.
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Old Aug 26, 2016 | 02:43 PM
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The 98-02 f bodies do use 4 heated O2's. Some of the 6 cyl engines use 3 O2's, but again heated. If you need a print I will send you a copy, pm me or give me a call 909 910 3867. Steve

Last edited by EFIHARNESS; Aug 26, 2016 at 03:14 PM.
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Old Aug 28, 2016 | 09:19 PM
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yea you're actually correct i was misinformed - bad sensor just not allowing heater readiness test to clear ... waiting for new one in the mail - no codes throwing anymore & runs perfect, but i've read here in a few posts that the passenger upstream is different somehow & the ecu can tell & with me having the downstream one currently in it's place i'm thinking heater readiness wont clear until i install the new specific/proper passenger side upstream sensor.
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Old Aug 28, 2016 | 10:45 PM
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All 4 of those O2's are electrically the same. the connectors are different so in the harness you will know which are before and after the cat for dtc's
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Old Aug 30, 2016 | 02:13 PM
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yea 6 miles of driving with new sensor & sensor heater readiness cleared so smog good to go ... so apparently the ecu detects if an improper one is in the passenger upstream, although yes i do agree that they are all the same build wise & mechanically/electrically.
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