### P0420 Catalyst System Efficiency Below Threshold
– Frequent Reasons:
Worn catalytic converter [1]
– Recommended Fixes:
Diagnose fuel trim https://carautorepair.site/
### P0171 System Too Lean
– Potential Issues:
Faulty MAF sensor
– Diagnostic Steps:
Inspect injectors [1][7]
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## Vehicle Service Vocabulary
### Electronic Braking System
– Function: Enables safe braking [7]
### Engine Management Unit
– Responsibility: Monitors sensors [7]
### Drivetrain Components
– Includes: Transmission [7]
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## Mechanical Fixing Workflow
1. **Problem Identification**:
Conduct road test
2. **Component Testing**:
Measure resistance
3. **Defective Unit Swap**:
Follow torque specs
4. **Post-Repair Verification**:
Confirm warning light reset
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## Essential Tools
| **Tool Type** | **Examples** | **Purpose** |
|—|—|—|
| Diagnostic Scanner | BlueDriver | Retrieve DTCs |
| Hand Instruments | Multimeter | Electrical testing |
—
## Service Information References
### Mechanical Information System
– Features:
Wiring diagrams [8]
Factory repair procedures
### Mobile Applications
– Vehicle Service App:
ECU pinouts [5]
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## Budget Repair Strategies
– Routine checkups extends vehicle life
– Learn basic diagnostics to avoid unnecessary repairs
– Install quality alternatives when OEM prices prohibitive [7]