### P0420 Catalyst System Efficiency Below Threshold
– Common Causes:
Worn catalytic converter [1]
– Suggested Repairs:
Replace catalytic converter https://carautorepair.site/
### P0171 Air-Fuel Ratio Error
– Potential Issues:
Fuel delivery problems
– Diagnostic Steps:
Inspect injectors [1][7]
—
## Vehicle Service Vocabulary
### Skid Prevention Technology
– Function: Enables safe braking [7]
### Engine Management Unit
– Responsibility: Manages fuel injection [7]
### Transmission System Parts
– Includes: Drive axles [7]
—
## Mechanical Fixing Workflow
1. **Initial Diagnosis**:
Perform visual inspection
2. **Part Evaluation**:
Measure resistance
3. **Defective Unit Swap**:
Use OEM parts
4. **Post-Repair Verification**:
Confirm warning light reset
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## Necessary Equipment
| **Tool Type** | **Examples** | **Purpose** |
|—|—|—|
| OBD-II Tool | Autel | Live data streaming |
| Mechanical Tools | Torque wrench | Electrical testing |
—
## Technical Data Resources
### Vehicle Service Database
– Features:
Component locations [8]
OEM specifications
### Mobile Applications
– Vehicle Service App:
Electrical diagrams [5]
—
## Cost-Saving Tips
– Preventative service prevents major failures
– Understand DTC meanings to prevent mechanic overselling
– Select certified components when budget constrained [7]
