P1166 HONDA - Air/Fuel Ratio Sensor 1 Heater Circuit Malfunction
- Faulty Air/Fuel Ratio Sensor 1
- Air/Fuel Ratio Sensor 1 harness is open or shorted
- Air/Fuel Ratio Sensor 1 circuit poor electrical connection
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When is the code detected?
- Engine Light ON (or Service Engine Soon Warning Light)
P1166 Honda Description
The Air/Fuel Ratio (A/F) sensor 1 is installed in the exhaust system and detects oxygen content in the exhaust gas. The A/F sensor transmits output voltage to the Engine Control Module (ECM). A heater for the sensor element is embedded in the A/F sensor (sensor 1). It is activated and heats the sensor to stabilize and speed the detection of oxygen content by controlling current flowing through the heater. An increase in the current levels off as the applied voltage to the element electrode reaches a certain range because the amount of oxygen which is led through the diffusion layer is limited. The current amperage is proportional to oxygen content in the exhaust gas, so the air/fuel ratio is detected by the measurement of the current amperage. The ECM compares a set target air/fuel ratio with the detected air/fuel ratio and controls the fuel injection timing.
If the A/F sensor (sensor 1) voltage is low, the air/fuel ratio is lean, and the ECM uses A/F feedback control to issue a Rich command. If the A/F sensor (sensor 1) voltage is high, the air/fuel ratio is rich, and the ECM uses A/F feedback control to issue a Lean command.
P1166 Honda Information for specific Honda models
P1166 1997 HONDA CIVIC
P1166 1998 HONDA CIVIC
P1166 1999 HONDA CIVIC
P1166 2000 HONDA CIVIC