COMPONENT LOCATION |
GENERAL DESCRIPTION |
The ECM uses dual oxygen sensors to monitor the efficiency of the manifold catalytic converter (warm-up catalytic converter). By monitoring the oxygen storage capacity of a catalyst, its efficiency can be indirectly calculated. The upstream HO2S is used to detect the amount of oxygen in the exhaust gas before it enters the catalytic converter. A low voltage indicates high oxygen contents (lean air mixture). A high voltage indicates low oxygen contents (rich air mixture). When the catalyst is working properly, it used oxygen in the exhaust. The oxygen levels coming out of the catalyst should be lower and a more stable level. This would produce a somewhat level HO2S reading around 700 to 800 mv. When the catalyst efficiency drops, no chemical reaction takes place. This means the concentration of oxygen will be the same at the rear as it is at the front of the catalyst. This will give a HO2S reading simular to the upstream sensor.
DTC DESCRIPTION |
If the oxygen storage time for Bank 1 is lower than threshold, the ECM determines that a fault exists and a DTC is stored .
DTC DETECTING CONDITION |
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Item | Detecting Condition | Possible cause | |||||||||||||||||||||||||||||||
DTC Strategy |
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EnableConditions |
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Threshold value |
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Diagnosis Time |
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MIL On Condition |
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MONITOR GDS DATA |
1. | Connect GDS to Data Link Connector(DLC). |
2. | IG “ON”. |
3. | Select “DTC” button, and then Press “DTC Status” to check DTC’s information from the DTCs menu. |
4. | Read “DTC Status” parameter. |
5. | Is parameter displayed “Present fault”? Â
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COMPONENT INSPECTION |
â– Monitor the Catalyst Converter |
1. | Clear DTC. |
2. | Start the engine and warm it up until the radiator fan comes on( more than at least 10 minutes). |
3. | Drive at a steady speed between 45-55 mph(72-88 km/h) for 30 seconds. |
4. | Stop and then maintain idle state for 120 seconds in D-position. |
5. | Repeat step 3 once again. |
6. | Stop and then keep it in idle state( D-positon) for 120 seconds. |
7. | Repeat step 3 once again. |
8. | Stop and then maintain idle state for 120 seconds in D-position. |
9. | IG “OFF” |
10. | Repeat steps 3 through 9 three times. |
11. | Check if catalyst monitoring readiness is complete. so, if the readiness is incomplete, repeat steps 2 through 10. |
12. | Does the scan tool show DTC P0420?? Â
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