P0154 Ho2S Circuit Insufficient Activity Bank 2 Sensor 1 - Isuzu 2000 Trooper Workshop Manual

P0154 HO2S Circuit Insufficient Activity Bank 2 Sensor 1

Circuit Description
The powertrain control module (PCM) supplies a bias
voltage of about 450 mV between the heated oxygen
sensor (HO2S) high and low circuits. When measured
with a 10 megaohm digital voltmeter, this may display as
low as 320 mV. The oxygen sensor varies the voltage
within a range of about 1000 mV when the exhaust is rich,
down through about 10 mV when exhaust is lean. The
PCM constantly monitors the HO2S signal during "closed
loop" operation and compensates for a rich or lean
condition by decreasing or increasing injector pulse width
as necessary. If the Bank 2 HO2S 1 voltage remains at or
near the 450 mV bias for an extended period of time, DTC
P0154 will be set, indicating an open sensor signal or
sensor low circuit.
Heated oxygen sensors are used to minimize the amount
of time required for "closed loop" fuel control operation
and to allow accurate catalyst monitoring. The oxygen
sensor heater greatly decreases the amount of time
required for fuel control sensors Bank 1 HO2S 1 and Bank
2 HO2S 1 to become active. Oxygen sensor heaters are
required by post-catalyst monitor sensors to maintain a
sufficiently high temperature for accurate exhaust oxygen
content readings further from the engine.
Conditions for Setting the DTC
D No related DTCs.
D Battery voltage is above 10 volts.
TROOPER 6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC)
D Engine running time is longer than 40 seconds.
D Oxygen sensor heater is functioning properly.
D Bank 2 HO2S 1 signal voltage remains between
400 mV and 500 mV for a total of 77 seconds over a
90-second period of time.
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.
D "Open loop" fuel control will be in effect.
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 P0154 will clear after 40 consecutive
warm-up cycles have occurred without a fault.
D DTC P0154 can be cleared by using the Tech 2 "Clear
Info" function or by disconnecting the PCM battery
feed.
Diagnostic Aids
Check for the following conditions:
D Poor connection or damaged harness – Inspect the
harness connectors
6E–207
D06RY00175
for backed-out terminals,