P0051 SUBARU - HO2S21 Heater Control Circuit Low
- Faulty Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1
- Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1 harness is open shorted
- Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1 circuit poor electrical connection
- Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1 fuse
- Faulty Engine Control Module (ECM)
When is the code detected?
- Engine Light ON (or Service Engine Soon Warning Light)
P0051 SUBARU Description
In order to achieve the require temperature, a heater element is included inside the heated oxygen sensor. The ECM controls the heated oxygen sensor heater element based on signals from the engine coolant temperature and engine load. The ECM controls the heater element circuit by allowing current flow to ground.
The ECM monitors the voltage signal received through the heater element circuit and determines the state of the circuit by comparing the voltage detected with the factory specifications.
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