850 Turbo L5-2.3L Turbo VIN 57 B5234FT (1996)
B5234T/B5234T5 (model year 95): HO2S pre-heating starts immediately after engine start, but can be interrupted during the first three minutes if
the engine slows to idling speed.
Heating of the rear HO2S is delayed by up to 7 minutes. This is done so as to ensure that the temperature around the HO2S units has had time to
rise, thus avoiding any risk of condensation.
B5254S: HO2S pre-heating begins immediately after engine start. When HO2S temperature reaches 350°C (662°F), HO2S temperature remains
constant until exhaust gas temperature at the front HO2S and TWC temperature at the rear HO2S reach levels where there is no risk of
condensation.
Both sensor terminals are connected to the ECM
When the engine is running rich (lambda<1), the oxygen content of the exhaust gases is low or zero and the output signal is approx. 0.9 Volts.
When the engine is running lean (lambda>1), the exhaust gases contain excess oxygen and the output signal falls to almost 0 Volt.
The change from high to low signal level occurs at the ideal (stoichiometric) air/fuel ratio of 14.2 kg/lkg (lbs / 1lb).
The ECM uses the HO2S signal to control the fuel injection so as to maintain the ideal value of lambda=1.
