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Discussion Starter #1
Sorry to bring up a very old thread. Having this exact same issue on a 2007 SX4. Car has brand new oxygen sensors, both the air fuel ratio sensor and sensor 2. Sensor 1 is a denso and sensor 2 is an NTK. Monitoring voltage on the brown wire at the oxygen sensor key one engine running, it starts out at 4.4v, it will eventually drop down below 1.0v but it takes probably around 2 minutes to do so. As I understand it this code will trigger if it sees over 1.2v for more then 5 seconds. We have tried a different pcm with the exact same issue, not sure what is going on here, checked continuity on the power wire to the sensor and it is good, has no voltage drop, checked all the grounds on the pcm, running out of things to try.
 

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99 Tracker, 5 door, 2L, 4x4
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You need to understand an AFR sensor is not the same as an )2 sensor...

AFR = 1vdc balanced
<1vdc = rich condition
.>1vdc = lean condition.

O2 B1S2 = post CAT ~.45 to.75 = good
 

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Note: It is best to start you own thread, Make sure you fill in the signature and information on your ride..

Welcome to the forum
 

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Discussion Starter #4
I understand the difference, once the engine is warmed up the sensor operates between .45 and .75, the problem im running into is that it takes a very long time to get down to that voltage, and the DTC will set because it is seeing above 1.2v for more then 5 seconds.
 

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Discussion Starter #5
Car has brand new oxygen sensors, both the air fuel ratio sensor and sensor 2. Sensor 1 is a denso and sensor 2 is an NTK. Monitoring voltage on the brown wire at the oxygen sensor key one engine running, it starts out at 4.4v, it will eventually drop down below 1.0v but it takes probably around 2 minutes to do so. As I understand it this code will trigger if it sees over 1.2v for more then 5 seconds. We have tried a different pcm with the exact same issue, not sure what is going on here, checked continuity on the power wire to the sensor and it is good, has no voltage drop, checked all the grounds on the pcm, running out of things to try.

The voltage will eventually drop down and fluctuate in the .45 to .75 area but it takes an extremely long time to do so, and of course it sets the DTC as it sees over 1.2v for more then 5 seconds. Which initially made me think the sensors heater is not doing its job, but at room temperature the heater circuit is at 6ohms which is in spec.
 

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I understand the difference, once the engine is warmed up the sensor operates between .45 and .75, the problem im running into is that it takes a very long time to get down to that voltage, and the DTC will set because it is seeing above 1.2v for more then 5 seconds.
If you are referring to the post O2 sensor, it should never over 1vdc, not ever..!..

If you are seeing >1vdc there is an issue.. Have you verified the heater at the O2 ?
 

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Discussion Starter #7
If you are referring to the post O2 sensor, it should never over 1vdc, not ever..!..

If you are seeing >1vdc there is an issue.. Have you verified the heater at the O2 ?
I created another thread, but yes the heaters tests out ok, tested it at 6ohms at room temperature, spec is 5-6.4ohms I believe.
 

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Some heater circuits are modulated, so you must check them with a test light or a scope.. 2 common coloured wires at the sensor are the heater circuit

Again, as stated in your other post, the post O2 sensor circuit should never see any reading over 1vdc...
 

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No need to pull it out, just leave it in the exhaust and back probe the connector..
 

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Discussion Starter #12
No I meant pull the car back in the shop, its in the parking lot right now lol ;)
 

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LOL, a language barrier... always test with the circuit loaded, open circuit voltage reading are invalid...
 
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