### P0420 Catalyst System Efficiency Below Threshold
– Typical Sources:
Exhaust leaks [1]
– Recommended Fixes:
Diagnose fuel trim https://carautorepair.site/
### P0171 System Too Lean
– Possible Defects:
Faulty MAF sensor
– Testing Procedure:
Smoke test intake [1][7]
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## Vehicle Service Vocabulary
### ABS (Anti-Lock Brake System)
– Purpose: Maintains steering control [7]
### ECM/ECU (Engine Control Module)
– Role: Monitors sensors [7]
### Powertrain Elements
– Includes: Transmission [7]
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## Repair Process Steps
1. **Symptom Assessment**:
Scan DTCs
2. **Component Testing**:
Test continuity
3. **Defective Unit Swap**:
Clear error codes
4. **Final Quality Check**:
Confirm warning light reset
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## Essential Tools
| **Tool Type** | **Examples** | **Purpose** |
|—|—|—|
| Diagnostic Scanner | Innova | Retrieve DTCs |
| Mechanical Tools | Smoke machine | Electrical testing |
—
## Repair Documentation Sources
### Auto Repair Source
– Features:
Wiring diagrams [8]
Technical illustrations
### Digital Assistants
– Auto Repair Documents:
Component testing guides [5]
—
## Affordable Maintenance Advice
– Preventative service extends vehicle life
– Learn basic diagnostics to avoid unnecessary repairs
– Use aftermarket parts when OEM prices prohibitive [7]