6E–185
TROOPER 6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC)
P0137 HO2S Circuit Low Voltage Bank 1 Sensor 2
D06RY00172
Circuit Description
The powertrain control module (PCM) supplies bias
voltage of about 450 mV between the heated oxygen
sensor (HO2S) signal high and signal low circuits. When
measured with a 10 megaohm impedance digital
voltmeter, this may display as low as 350 mV. The
oxygen sensor varies the voltage within a range of about
1000 mV when exhaust is rich, down through about
10 mV when the 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 1 HO2S 2 signal voltage remains
excessively low for an extended period of time, DTC
P0137 will be set.
Conditions for Setting the DTC
D
No related DTCs.
D
Engine is operating in “closed loop.”
D
Engine coolant temperature is above 60
°
C (140
°
F).
D
“Closed loop” commanded air/fuel ratio is between
14.5 and 14.8.
D
Throttle angle is between 3% and 19%.
D
Bank 1 HO2S 2 signal voltage remains below 22 mV
during normal “closed loop” operation for a total of 106
seconds over a 125-second period of time.
OR
D
Bank 1 HO2S 2 signal voltage remains below 400 mV
during power enrichment mode fuel control operation
for up to 5 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 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 P0137 will clear after 40 consecutive
warm-up cycles have occurred without a fault.
D
DTC P0137 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
Heated oxygen sensor wiring – The sensor pigtail may
be mispositioned and contacting the exhaust system.
D
Poor PCM to engine grounds.
D
Fuel pressure – A condition which causes a lean
exhaust can cause DTC P0137 to set. The system will
go lean if pressure is too low. The PCM can