Daewoo Matiz (2003 year). Manual - part 47
1F – 98 ENGINE CONTROLS
MAA1F140
DIAGNOSTIC TROUBLE CODE (DTC) – P0138 HEATED OXYGEN SENSOR HIGH
VOLTAGE
Circuit Description
The engine control module (ECM) supplies a voltage of
about 450mm volts between the ECM terminals 64 and
13. The Heated oxygen (O
2
) 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 Heated
O
2
sensor is like an open circuit and produces no volt-
age when it is below 360
°
C(600
°
F). An open O
2
sensor
circuit or a cold O
2
sensor causes “open loop” operation.
Conditions for Setting the DTC
D
The Heated oxygen sensor voltage is more than 4.8V
for at least 0.2 seconds.
D
A high voltage condition exists.
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.
Diagnostic Aids
D
Normal scan tool voltage varies between 0.1volts and
0.9volts while in closed loop.
D
Inspect the oxygen (O
2
) sensor wire. The O
2
sensor
may be positioned incorrectly and contacting the ex-
haust manifold.
D
Check for an intermittent ground in the wire between
the O
2
sensor and the engine control module.
D
Perform an injector 2alance test to determine if a re-
stricted fuel injector may be causing the lean condi-
tion.
D
Vacuum of crankcase leaks will cause a lean running
condition.
D
An exhaust manifold gasket leak of a cracked ex-
haust manifold may cause outside air to be pulled into
the exhaust and past the sensor.