P0141
Symptom: The CHECK ENGINE lamp (MIL) is on.
Heating, rear heated oxygen sensor
Symptom of fault
The CHECK ENGINE lamp (MIL) is on.
Conditions
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•
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Heating circuit current below 500 mA or above 2300 mA for 5
seconds.
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Note
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Oxygen sensor heating is activated at engine coolant temperatures above
50°C (122°F).
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|
Diagnostic help
The oxygen sensor's heating circuit current can be ascertained using an ISAT
scan tool.
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-
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Select
"READ FUNCTIONS".
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-
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Select
"PREHEAT OXY SENSOR REAR"
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With the engine hot, the ISAT scan tool should show a heating current of 700-
1000 mA. Oxygen sensor heating can be activated by means of the ISAT scan
tool.
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-
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Select
"OXY SENSOR REAR".
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If diagnostic trouble codes P0135 and P0141 are present, the cause of the fault
is:
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•
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because fuse 38 has
blown
|
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•
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in the lead between pin 8 of H33-4 and pin 87 of the pump
relay
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Checking the wiring. Intermittent faults may occur as a result of occasional short
circuits and breaks in the wiring. Jiggle the leads and in-line connectors at several places and
in different directions to reveal faults in the wiring harness. Observe the multimeter, ISAT scan
tool or test lamp while carrying out this check.
Diagnostic procedure
1. Check additional diagnostic trouble codes in the Trionic
system
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-
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Obtain readouts of all diagnostic
trouble codes using the ISAT scan tool.
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Are P0135 and P0141 present?
Continue with point 2.
Continue with point 3.
2. Check the oxygen sensors' heating circuit
resistance
The engine should have been switched off for at least 5 minutes.
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-
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Check fuse 38 and change it if
necessary
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-
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Unplug the 4-pin connectors of
both oxygen sensors.
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|
-
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Check the resistance of both
sensors:
across pins 1-2
__________ar;_______ _ 1.8-4.0
ohms
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Are the resistance readings OK?
Repair or replace the leads between pin 1 of the connectors of both oxygen
sensors and fuse 38. Then continue with point 4.
Change the relevant oxygen sensor and proceed to point 4.
3. Check the heating circuit ground connection
and power supply
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-
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Unplug the oxygen sensor's
4-pin connector
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-
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Start the engine and run it at idling
speed until the coolant temperature is above 50°C (122°F).
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-
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Connect the test lamp to:
• pin 1 and battery negative (B-)
• B+ and pin 2
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Does the test lamp light up in both cases?
Change the sensor and continue with point 4.
Rectify the lead in question and proceed to point 4.
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Note
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The rear heated oxygen sensor's heating circuit is not activated until the engine
coolant temperature rises above 50°C
(122°F).
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4. Final check
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-
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Clear the diagnostic trouble
code.
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|
-
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Implementation of driving cycle:
Drive the car at varying engine rpm and loads for 5 minutes.
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-
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Evaluation of driving cycle: Check
whether the diagnostic trouble code has recurred.
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Has the diagnostic trouble code recurred?
Proceed to
.
The remedial measure taken was correct.
