### P0420 Catalyst System Efficiency Below Threshold
– Frequent Reasons:
Faulty oxygen sensor [1]
– Common Solutions:
Diagnose fuel trim https://carautorepair.site/
### P0171 Air-Fuel Ratio Error
– Possible Defects:
Vacuum leaks
– Diagnostic Steps:
Smoke test intake [1][7]
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## Car Maintenance Terms
### Skid Prevention Technology
– Purpose: Prevents wheel lockup [7]
### ECM/ECU (Engine Control Module)
– Responsibility: Manages fuel injection [7]
### Drivetrain Components
– Includes: Differential [7]
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## Service Procedure Stages
1. **Symptom Assessment**:
Scan DTCs
2. **Component Testing**:
Measure resistance
3. **Component Installation**:
Follow torque specs
4. **Post-Repair Verification**:
Ensure proper operation
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## Critical Instruments
| **Tool Type** | **Examples** | **Purpose** |
|—|—|—|
| OBD-II Tool | BlueDriver | Live data streaming |
| Mechanical Tools | Multimeter | Electrical testing |
—
## Service Information References
### Vehicle Service Database
– Capabilities:
Wiring diagrams [8]
Technical illustrations
### Digital Assistants
– Auto Repair Documents:
ECU pinouts [5]
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## Affordable Maintenance Advice
– Routine checkups prevents major failures
– Understand DTC meanings to avoid unnecessary repairs
– Select certified components when OEM prices prohibitive [7]