### P0420 Catalyst System Efficiency Below Threshold
– Common Causes:
Exhaust leaks [1]
– Recommended Fixes:
Diagnose fuel trim https://carautorepair.site/
### P0171 System Too Lean
– Likely Problems:
Fuel delivery problems
– Testing Procedure:
Inspect injectors [1][7]
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## Car Maintenance Terms
### ABS (Anti-Lock Brake System)
– Function: Enables safe braking [7]
### Vehicle Computer System
– Role: Monitors sensors [7]
### Transmission System Parts
– Contains: Transmission [7]
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## Service Procedure Stages
1. **Symptom Assessment**:
Perform visual inspection
2. **Part Evaluation**:
Measure resistance
3. **Defective Unit Swap**:
Clear error codes
4. **System Validation**:
Test drive vehicle
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## Critical Instruments
| **Tool Type** | **Examples** | **Purpose** |
|—|—|—|
| Diagnostic Scanner | Autel | Retrieve DTCs |
| Mechanical Tools | Torque wrench | Component repair |
—
## Technical Data Resources
### Auto Repair Source
– Capabilities:
Wiring diagrams [8]
OEM specifications
### Smartphone Tools
– Auto Repair Documents:
Electrical diagrams [5]
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## Cost-Saving Tips
– Preventative service avoids costly repairs
– Master code scanning to avoid unnecessary repairs
– Select certified components when OEM prices prohibitive [7]