### P0420 Catalyst System Efficiency Below Threshold
– Common Causes:
Exhaust leaks [1]
– Suggested Repairs:
Repair exhaust system https://carautorepair.site/
### P0171 Air-Fuel Ratio Error
– Possible Defects:
Faulty MAF sensor
– Diagnostic Steps:
Check fuel pressure [1][7]
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## Vehicle Service Vocabulary
### Electronic Braking System
– Purpose: Maintains steering control [7]
### Engine Management Unit
– Responsibility: Controls ignition timing [7]
### Transmission System Parts
– Contains: Drive axles [7]
—
## Service Procedure Stages
1. **Symptom Assessment**:
Perform visual inspection
2. **System Verification**:
Measure resistance
3. **Parts Replacement**:
Use OEM parts
4. **Post-Repair Verification**:
Test drive vehicle
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## Necessary Equipment
| **Tool Type** | **Examples** | **Purpose** |
|—|—|—|
| OBD-II Tool | Autel | Retrieve DTCs |
| Physical Equipment | Torque wrench | Component repair |
—
## Repair Documentation Sources
### Auto Repair Source
– Capabilities:
Component locations [8]
Technical illustrations
### Digital Assistants
– Auto Repair Documents:
Component testing guides [5]
—
## Cost-Saving Tips
– Preventative service extends vehicle life
– Learn basic diagnostics to avoid unnecessary repairs
– Select certified components when OEM prices prohibitive [7]