No
Intermittent Fault. Refer to
Yes
Step 8
Diagnostic completed.
5. Repair Instructions:
Replace the pre-catalytic oxygen sensor. Refer to
Pre-Catalytic Oxygen Sensor Replacement
.
2.12.7.24 DTC P0137 P0138 P0140
1. DTC Descriptor:
DTC
P0137
Post-Catalytic Oxygen Sensor Circuit Short To Low Voltage
DTC
P0138
Post-Catalytic Oxygen Sensor Circuit Short To High Voltage
DTC
P0140
Post-Catalytic Oxygen Sensor Circuit Open
After the vehicle started, ECM works in open-loop mode, in which ECM ignores the Pre-Catalytic oxygen sensor signal voltage when
calculating the Air-Fuel ratio. ECM provides an approximate 450 mV reference voltage to the Pre-Catalytic oxygen sensor. When
the engine is running, Pre-Catalytic oxygen sensors start heating and begin to generate a 0-0.1 V voltage, which fluctuates. Once
ECM detects that the Pre-Catalytic oxygen sensor voltage exceeds a preset threshold voltage, ECM immediately enters into the
closed-loop mode. ECM uses Pre-Catalytic oxygen sensor signal voltage to determine the Air-Fuel ratio. If the Pre-Catalytic oxygen
sensor voltage is increased to above the reference voltage (tend to 1 V), the mixture is too rich. If the Pre-Catalytic oxygen sensor
the voltage decreased to below the reference voltage (tend to 0 mV), the mixture is too lean.
•
ECM provides a signal through ECM harness connector EO01 terminal No.30 to Post-Catalytic oxygen sensor wiring harness
connector EO03 terminal B.
•
ECM provides an internal low reference voltage through ECM harness connector EO01 terminal No.55 to Pre-Catalytic oxygen
sensor wiring harness connector EO03 terminal No.A.
2. Conditions For Setting DTC and The Fault Location:
DTC Code DTC Detection Strategy Conditions For Setting The DTC (Control Strategy)
Fault Locations
P0137
Short to Ground When Cold
1. Engine running longer than 60 s.
2. Coolant temperature is less than 70 °C (158 ºF).
3. Post-Catalytic oxygen sensor signal 0.
4. Duration longer than 25 s.
1. Sensor circuit
2. Sensor
3. ECM
P0138
Post-Catalytic oxygen
sensor voltage signal too
high
1. Engine running longer than 60 s.
2. Coolant temperature is less than 70 °C (158 ºF).
3. Post-Catalytic oxygen sensor signal around 3,200
mV.
4. Duration longer than 25 s.
2-680
Control System JL4G15-D
Engine
EC718/EC718RV EC715/EC715RV 10/2009
Summary of Contents for EC715 2009
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