P0152 Ho2S Circuit High Voltage Bank 2 Sensor 1 - Isuzu 2000 Trooper Workshop Manual

6E–200
TROOPER 6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

P0152 HO2S Circuit HIGH Voltage 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) signal high and signal 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 the injector
pulse width as necessary. If the Bank 2 HO2S 1 voltage
remains excessively high for an extended period of time,
DTC P0152 will be set.
Conditions for Setting the DTC
D No related DTCs.
D The engine is operating in "closed loop."
D The engine coolant temperature is above 60°C
(140°F).
D "Closed loop" commanded air/fuel ratio between 14.5
and 14.8.
D Bank 2 HO2S 1 signal voltage remains above 952 mV
during normal "closed loop" operation for a total of 77
seconds over a 90-second period.
OR
D Bank 2 HO2S 1 signal voltage remains above 500 mV
during deceleration fuel cutoff mode operation for up to
3 seconds.
Diagnostic Trouble Code (DTC)
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 P0152 will clear after 40 consecutive
warm-up cycles have occurred without a fault.
D DTC P0152 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 Fuel pressure – The system will go rich if pressure is
too high. The PCM can compensate for some
increase. However, if fuel pressure is too high, a DTC
P0152 may be set. Refer to Fuel System Diagnosis .
D Rich injector(s) – Perform "Injector Balance Test."
D Leaking injector – Refer to Fuel System Diagnosis .
D Evaporative emissions (EVAP) system – Check the
canister for fuel saturation. If the canister is full of fuel,
check EVAP control system components and hoses.
D06RY00174