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Does anybody have any idea which oxygen sensor is linked to the message "HO2S Bank 1, Sensor 2 Heater Circuit Low?"
Assuming I had to choose, I'd say the most difficult one to reach.
Yours faithfully.
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Code 2011 (P0037). Highlander Performance
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GoodWillHunt
- Posts: 40
- Joined: Mon Feb 02, 2026 8:37 pm
It's true what they say about "automotive Murphy's Law": the hardest one to reach is..." It seems like the universe is finally on your side, which is great news. The downstream oxygen sensor, situated after the catalytic converter, is referenced by the "Bank 1, Sensor 2" code.
Unlike its upstream sibling, Sensor 1, which is located in the cramped and hot engine bay, this sensor is usually located in the exhaust pipe underneath the car, making it the easier to access. When you see the "Heater Circuit Low" portion of the code, it usually means that the sensor's internal heater has failed. However, before you start removing connections and inspecting wiring, make sure that there is no corrosion or damage.
Unlike its upstream sibling, Sensor 1, which is located in the cramped and hot engine bay, this sensor is usually located in the exhaust pipe underneath the car, making it the easier to access. When you see the "Heater Circuit Low" portion of the code, it usually means that the sensor's internal heater has failed. However, before you start removing connections and inspecting wiring, make sure that there is no corrosion or damage.
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Imlach_C220
- Posts: 34
- Joined: Mon Feb 02, 2026 8:46 pm
Hi-O2S stands for "Heated Oxygen Sensor."