Causes and Fixes Nissan P1148 Code: Closed Loop Bank 1

How to fix a Nissan P1148 engine Code: Closed Loop Bank 1 (Control Function Fault Detected)
How To Test Oxygen Sensor Heater Element Video:
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How To Test Upstream Oxygen Sensor 1 Video:    • How To Test Upstream Oxygen Sensor 1 ...  

A closed loop is when the computer (ECM/PCM) is using the Oxygen Sensor for feedback.
An open loop is when the computer (ECM/PCM) is Not using the Oxygen Sensor for feedback.
An open loop is normal when the engine first starts.
Once the engine warms up, it should go into a closed loop.

Possible Causes of a Nissan P1148 Code:
Faulty Air Fuel Ratio Sensor-1 Bank-1
Wiring Open or Short
Blown Fuse
Exhaust Leak

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