1F–100 ENGINE CONTROLS
DAEWOO M-150 BL2
MAA1F140
DIAGNOSTIC TROUBLE CODE (DTC) – P0140 HEATED OXYGEN SENSOR NO
ACTIVITY
Circuit Description
The engine control module (ECM) supplies a voltage of
about 450mm volts between the ECM terminals 64 and
13. The oxygen (O2) sensor varies the voltage within a
range of about 1volt if the exhaust is rich, down to about
100mm volts if the exhaust is lean. The O2 sensor is like
an open circuit and produces no voltage when it is below
360°C(600°F). An open O2 sensor circuit or a cold O2
sensor causes “open loop” operation.
Conditions for Setting the DTC
D The engine controls system is in closed loop.
D Engine Coolant Temperature is higher than 70°C
(140°F).
D The mass air flow(MAF) is between 25kg/h and
50kg/h.
D The engine speed is between 2,400rpm and 300rpm.
D The vehicle speed is between 64km/h(12.4mph) and
80km/h(24.9mph).
D The manifold air pressure is higher than 70kPa.
D The ignition is at 10 volts.
D No transition from rich side to lean side or lean side to
rich side during 7.8 seconds even with a forcing of O2
sensor controller.
D DTCs P0107, P0108, P0112, P0113, P0117, P0118,
P0122, P0123, P0137, P0138, P0137, P0138,
P0137, P0138, P1671, P0300, P0335, P0336,
P0341, P0400, P0404, P0405, P0644, P0645 are
NOT SET.
Action Taken when the DTC Sets
D Emission related.
D “Armed” after two trip with a fail.
D “Disarmed” after one trip with a pass.
D MIL on if failure is detected in three consecutive trips.
D Stores a History DTC on the third consecutive with a
fail (The DTC will be armed after the second fail).
D Stores a Freeze Frame on the third consecutive trip
with a fail (if empty).
Conditions for Clearing the MIL/DTC
D The MIL will turn off after four consecutive ignition
cycles in which the diagnostic runs without a fault.
D A history DTC will clear after 40 consecutive warm up
cycles without a fault.
D DTC(s) can be cleared by using the scan tool.
D Disconnecting the ECM battery feed for 10 seconds.
Diagnostic Aids
D Normal scan tool voltage varies between 0.15 to
8.5mV while in Closed Loop. If DTC P0140 is inter-
mittent, refer to “Intermittent” in this Section.
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