General Information

P2197 O2 Sensor Signal Stuck Lean (Bank 2 Sensor 1)

General Information

Component Location





General Description

The PCM uses heated oxygen sensors (HO2S) placed before and after the catalytic converter to monitor the oxygen content of the exhaust. The front HO2S signal is used by the PCM to calculate air/fuel ratios when in closed loop operation. The signal, of the HO2S placed after the catalytic converter, is used to monitor the operation of the front HO2S and the catalytic converter. The HO2S generates a voltage signal which indicates the difference of oxygen content of the exhaust and the ambient air. The HO2S will generate a higher voltage signal (rich), when the exhaust has a lower content of oxygen than ambient air.

DTC Description

Checking output signals from HO2S under detecting condition, if HO2S's signal is lean during power enrichment conditions, PCM sets P2197.

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 0.6 V ~ 1.0 V. At idle, HO2S signal will switch from lean to rich at 3 Hz, on acceleration, its frequency increases.