General Information

Engine Control
P2270 O2 Sensor Signal Stuck Lean (Bank 1 Sensor 2) - General Information

Component Location





General Description

The rear HO2S is mounted on the flow side of the exhaust system after the catalytic converter. The location of this HO2S also monitors the operation of the HO2S located in front of the catalytic converter. In a normal operating system at operating temperature, the HO2S voltage signal is typically between 0V and 1V. This signal is normally linear when compared to the high activity of the front catalytic converter HO2S signal. When the voltage signal of the rear sensor follows the same activity of the front HO2S, it could be due to age, contamination of converter, or misfires.

DTC Description

Checking output signals from HO2S under detecting condition, if HO2S's signal is lean during power enrichment conditions, PCM sets P2270. MIL(Malfunction Indication Lamp) turns on when the malfunction lasts till consecutive 2 driving cycles.

DTC Detecting Condition





Specification





Diagnostic Circuit Diagram





Signal Waveform & Data












Fig 1) Normal waveforms of upstream HO2S(the upper) and downstream HO2S(the lower) (chassis ground used)
Fig 2) Normal waveforms of upstream HO2S(the upper) and downstream HO2S(the lower) (sensor ground used)
Fig 3) Normal graph of upstream HO2S and downstream HO2S at idle.

When at operating temperature, if accelerator pedal is released suddenly, around 4000 rpm, the HO2S signal reading will be lower than 200 mV, resulting from Fuel cut-off for the moment. Conversely, with sudden accelerator pedal depress, HO2S signal reading will be around 0.6V ~1.0V. At idle, HO2S signal will switch from lean to rich at 3 Hz, on acceleration, its frequency increases.