### P0420 Catalyst System Efficiency Below Threshold
– Common Causes:
Worn catalytic converter [1]
– Recommended Fixes:
Diagnose fuel trim https://carautorepair.site/
### P0171 Air-Fuel Ratio Error
– Likely Problems:
Fuel delivery problems
– Troubleshooting Process:
Smoke test intake [1][7]
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## Car Maintenance Terms
### Electronic Braking System
– Purpose: Prevents wheel lockup [7]
### Engine Management Unit
– Responsibility: Controls ignition timing [7]
### Transmission System Parts
– Includes: Differential [7]
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## Repair Process Steps
1. **Symptom Assessment**:
Scan DTCs
2. **System Verification**:
Check voltage
3. **Component Installation**:
Follow torque specs
4. **Final Quality Check**:
Test drive vehicle
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## Essential Tools
| **Tool Type** | **Examples** | **Purpose** |
|—|—|—|
| Code Reader | BlueDriver | Retrieve DTCs |
| Hand Instruments | Multimeter | Component repair |
—
## Repair Documentation Sources
### Auto Repair Source
– Features:
TSB access [8]
OEM specifications
### Digital Assistants
– Auto Repair Documents:
Electrical diagrams [5]
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## Budget Repair Strategies
– Routine checkups prevents major failures
– Understand DTC meanings to avoid unnecessary repairs
– Use aftermarket parts when budget constrained [7]
