General Precautions of EFI System Maintenance
F-29
32. P0136 Downstream Oxygen Sensor Signal Irrational
Description about Malfunction Cause:
After engine has been started, ECU performs measurement on circuit voltage of downstream oxygen
sensor, and will determine it to be the signal circuit of downstream oxygen sensor short to ground, when
signal voltage is lower than 0.4V for a long time.
Required Equipment: (Diagnostic Instrument with EOBD Diagnostic Function)
Step I: Use diagnostic instrument to read the malfunction information
Read Result I Read Result II
MIL Lamp On P-CODE Present MIL Lamp Off P-CODE Present
P0136 P0136
Maintenance tips:
The malfunction has been confirmed, and the
following problems may possibly exist
1) Downstream oxygen sensor is damaged and
should be replaced
Maintenance tips:
The malfunction has not been finally confirmed; wait
for ECU to fulfill the final test.
33. P0137 Downstream oxygen sensor signal circuit voltage too low (malfunction of circuit
short to ground)
Description about Malfunction Cause:
After engine has been started, ECU examines voltage of downstream oxygen sensor circuit. If signal voltage
is less than 0.06V longtime, it is determined to be the malfunction of downstream oxygen sensor signal circuit
short to ground.
Schematic Circuit:
Main relay
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