Geely EC718 2009 Workshop Manual page 762

2-680 Control System JL4G15-D
Yes
Diagnostic completed.
Step 8
5. Repair Instructions:
Replace the pre-catalytic oxygen sensor. Refer to
2.12.7.24 DTC P0137 P0138 P0140
1. DTC Descriptor:
DTC P0137
DTC P0138
DTC P0140
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)
P0137 Short to Ground When Cold
Post-Catalytic oxygen
P0138 sensor voltage signal too
high
EC718/EC718RV EC715/EC715RV 10/2009
2.4.7.2 Pre-Catalytic Oxygen Sensor
Post-Catalytic Oxygen Sensor Circuit Short To Low Voltage
Post-Catalytic Oxygen Sensor Circuit Short To High Voltage
Post-Catalytic Oxygen Sensor Circuit Open
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. 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.
Intermittent Fault. Refer to
No
Fault Check
Replacement.
Engine
2.2.7.3 Intermittent
Fault Locations
1. Sensor circuit
2. Sensor
3. ECM