P0158 Ho2S Circuit High Voltage Bank 2 Sensor - Isuzu 2000 Trooper Workshop Manual

6E–216
TROOPER 6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

P0158 HO2S Circuit High Voltage Bank 2 Sensor 2

Circuit Description
To control emissions of hydrocarbons (HC), carbon
monoxide (CO), and oxides of nitrogen (NOx), a
three-way catalytic converter is used. The catalyst within
the converter promotes a chemical reaction which
oxidizes the HC and CO present in the exhaust gas,
converting them into harmless water vapor and carbon
dioxide. The catalyst also reduces NOx, converting it to
nitrogen. The powertrain control module (PCM) has the
ability to monitor this process using the Bank 2 HO2S 1
and the Bank 2 HO2S 2 heated oxygen sensors. The
Bank 2 HO2S 1 sensor produces an output signal which
indicates the amount of oxygen present in the exhaust
gas entering the three-way catalytic converter. The Bank
2 HO2S 2 sensor produces an output signal which
indicates the oxygen storage capacity of the catalyst; this
in turn indicates the catalyst's ability to convert exhaust
gases efficiently. If the catalyst is operating efficiently, the
Bank 2 HO2S 1 signal will be far more active than that
produced by the Bank 2 HO2S 2 sensor. If the Bank 2
HO2S 2 signal voltage remains excessively high for an
extended period of time, DTC P0158 will be set.
Conditions for Setting the DTC
D No related DTCs.
D Engine is operating in "closed loop."
D "Closed loop" commanded air/fuel ratio is between
14.5 and 14.8.
Diagnostic Trouble Code (DTC)
D Engine coolant temperature is above 60°C (140°F).
D Bank 2 HO2S 2 signal voltage remains above 952 mV
during normal "closed loop" operation for a total of 106
seconds over a 125-second period.
OR
D Bank 2 HO2S 2 signal voltage remains above 500 mV
during deceleration fuel cutoff mode operation for up to
3 seconds.
Action Taken When the DTC Sets
D The PCM will illuminate the malfunction indicator lamp
(MIL) the first time the fault is detected.
D The PCM will store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.
Conditions for Clearing the MIL/DTC
D The PCM will turn the MIL "OFF" on the third
consecutive trip cycle during which the diagnostic has
been run and the fault condition is no longer present.
D A history DTC P0158 will clear after 40 consecutive
warm-up cycles have occurred without a fault.
D DTC P0158 can be cleared by using the Tech 2 "Clear
Info" function or by disconnecting the PCM battery
feed.
D06RY00177