I have a 1999 SR5 4Runner (6 cyl, Auto, CA model) that I can't get to pass smog just because the hO2 sensor (I'm assuming that this is the upstream one) won't reset. Everything else has reset and is good to go, but the hO2 sensor hasn't reset yet. Now I've replaced both O2 sensors, cleaned the MAF, disconnected the battery, and now have driven over 500 miles and it still hasn't reset. What am I doing wrong here? Have I just not done the crazy driving sequence right (I've tried). I need to get this past smog so I can start driving it again. Any help is appreciated...
Another Stupid Smog Question - hO2 Isn't Resetting
- Thread starter Racer_X
- Start date
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19963.4lsr5
New member
I think that’s the heater circuit.
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Can you confirm the part numbers for the sensors you replaced? I believe the correct upstream is 234-9002 and the correct downstream is 234-4153. Those numbers assume you replaced with Densos. The upstream is the heated O2 sensor.
19963.4lsr5
New member
The cat and EVAP monitors are the two that take a drive cycle to complete. If those are already set driving it more won’t do anything.
Can you post a snapshot of all the readiness monitors and their status?
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Can you post a snapshot of all the readiness monitors and their status?
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19963.4lsr5
New member
This is how my Innova displays the monitors.
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