The linear O2 sensor is mounted on the front side of the Catalytic Converter (warm-up catalytic converter) or in the front exhaust pipe. It detects a wide range of air/fuel ratios in the exhaust gas from the rich to lean regions. This linear O2 sensor produces a current that corresponds to a specific air/fuel ratio. The PCM monitors this signal and determines whether the air/fuel mixture is rich or lean. The PCM constantly monitors the linear O2 sensor and increases or decreases the fuel injection duration using this signal. This is called closed-loop fuel control operation.
The PCM monitors front O2 sensor pumping current circuit(VIP) and sets DTC P2237 if front O2 sensor signal stuck is detected.
Item
Detecting Condition
Possible cause
DTC Strategy
Pumping current circuit open (VIP)
Poor connection or damaged harness
Open in HO2S control circuit
Front HO2S
Enable Conditions
Wide range sensor pump current valid
Threshold value
Symptom detected on no activity
Signal < 2.1V during fuel cut off
Diagnosis Time
Within 15 sec. after related symptom detected.
MIL On Condition
2 driving cycle