Geely EC718 2009 Workshop Manual page 250

2-168 Control System JL4G18-D
Yes
Diagnostic completed.
Step 13
5. Repair Instructions:
Replace the CMP sensor. Refer to
2.2.7.32 DTC P0420
1. DTC Descriptor:
DTC P0420
ECM uses two oxygen sensors (Pre-Catalytic oxygen sensor and Post-Catalytic oxygen sensor) installed before and after the three-
way catalytic converters to monitor the conversion efficiency of the three-way catalytic converter (TWC). ECM uses Pre-Catalytic
oxygen sensor for Air-Fuel ratio close-loop control and monitors oxygen content in the exhaust gas not purified by TWC. The Post-
Catalytic oxygen sensor sends voltage signal to ECM indicating the oxygen content in the exhaust gas purified by the TWC. ECM
compares signals from the two sensors to determine whether the TWC is currently under normal working condition. If the calculated
TWC conversion efficiency is too low, the fault lamp will be lit and the DTC code will be set.
2. Conditions For Setting DTC and The Fault Location:
DTC Code DTC Detection Strategy
P0420 Exceed the Maximum Limit
3. Schematic:
Refer to 2.2.6.1 Schematic
4. Diagnostic Steps:
Note
Before carrying out this diagnosis step, observe the data list on scan tool and analyze the accuracy of the data, as
these will help with quick diagnosis.
Step 1 Check whether there are control system DTC codes other than DTC P0420.
EC718/EC718RV EC715/EC715RV 10/2009
2.10.8.1 Camshaft Position Sensor
Three-way Catalytic Converter Oxygen Storage Capacity Aging (Emission Over the Limit)
Conditions For Setting The DTC
1. After adjustment, the post-
catalytic oxygen sensor signal is
greater than the average
amplitude, which is 0.48 V.
2. Catalytic converter monitoring
activation time is greater than 70
s.
Intermittent Fault. Refer to
No
Fault Check
Replacement.
(Control Strategy)
(a) Connect scan tool to the datalink connector.
(b) Turn the ignition switch to "ON" position.
(c) Press the scan tool power button.
(d) Select the following menu items: Engine/Read DTC codes.
(e) Read DTC codes.
2.2.7.3 Intermittent
Fault Locations
1. Pre-Catalytic Oxygen Sensor
2. Post-Catalytic Oxygen Sensor
3. Three-way Catalytic Converter
4. Exhaust Leakage
Engine