Daewoo CIELO EURO III Manual page 345

System voltage is greater than 10 volts.
No related malfunctions (See P0131) and DTC
P0141 is not set.
Closed loop (C/L) test:
HO2S 2 voltage is greater than 0.952 volts.
3 second delay after in C/L.
Decel Fuel Cut-Off (DFCO) test:
HO2S 2 is greater than 0.478 volt. In DFCO.
3 second delay after in DFCO.
Action Taken When the DTC Sets
The Malfunction Indicator Lamp (MIL) will illuminate
after three (1.5L SOHC) or
consecutive trip with a fail.
The ECM will record operating conditions at the
time the diagnostic fails. This information will be
stored in the Freeze Frame and Failure Records buff-
ers.
A history DTC is stored.
Conditions for Clearing the MIL/DTC
The MIL will turn off after three (four –
1.5L SOHC) consecutive ignition cycles in which the
diagnostic runs without a fault.
A history DTC will clear after 40 consecutive warm up
cycles without a fault.
The DTC(s) can be cleared by using the scan tool.
DAEWOO T-154 BL2,3
ENGINE CONTROLS 1F – 176
Diagnostic Aids
Rich exhaust – An overly rich exhaust may load the
catalyst, causing high HO2S 2 signal voltages.
Silicone contamination – A false rich condition may
be caused by silicone contamination of the HO2S 2.
This will be indicated by a powdery white deposit on
the sensor.
Faulty HO2S 2 – If HO2S 2 is internally shorted, the
HO2S 2 voltage displayed on a scan tool will be over
1 volt. Disconnect the HO2S 2 and jumper the sensor
low circuit to engine ground; if the displayed voltage
goes from over 1000 mv to around 450 mv, replace
the HO2S 2.
Intermittent test – Observe HO2S 2 on scan
tool while moving related connectors and the wiring
harness with the key ON. If the failure is induced, the
HO2S 2 display will change. This may help isolate the
location of the malfunction.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Table.
1. The On-Board Diagnostic (EOBD) System Check
prompts the technician to complete some basic
checks and to store the freeze frame and failure re-
cords data on the scan tool if applicable. This
creates an electronic copy of the data taken when
the malfunction occurred. The information is then
stored on the scan tool for later reference.
2. This step determines if DTC P0138 is the result of a
hard failure or an intermittent condition.
5. Disconnecting the HO2S 2 and jumpering the sensor
signal circuit and the sensor low circuit to ground
should cause the scan tool to display HO2S 2 volt-
age below 100 mv (0.1 v). If the signal voltage is still
high, the ECM is malfunctioning.
8. The replacement ECM must be repro-
grammed. Refer to the latest Techline procedure for
ECM reprogramming.