### P0420 Catalyst System Efficiency Below Threshold
– Frequent Reasons:
Faulty oxygen sensor [1]
– Suggested Repairs:
Diagnose fuel trim https://carautorepair.site/
### P0171 Air-Fuel Ratio Error
– Possible Defects:
Fuel delivery problems
– Diagnostic Steps:
Smoke test intake [1][7]
—
## Vehicle Service Vocabulary
### Electronic Braking System
– Purpose: Maintains steering control [7]
### Engine Management Unit
– Role: Controls ignition timing [7]
### Transmission System Parts
– Includes: Drive axles [7]
—
## Service Procedure Stages
1. **Problem Identification**:
Conduct road test
2. **System Verification**:
Test continuity
3. **Component Installation**:
Follow torque specs
4. **System Validation**:
Test drive vehicle
—
## Critical Instruments
| **Tool Type** | **Examples** | **Purpose** |
|—|—|—|
| Diagnostic Scanner | Innova | Live data streaming |
| Hand Instruments | Multimeter | Electrical testing |
—
## Technical Data Resources
### Mechanical Information System
– Features:
Component locations [8]
Technical illustrations
### Digital Assistants
– Auto Repair Documents:
Electrical diagrams [5]
—
## Cost-Saving Tips
– Regular maintenance avoids costly repairs
– Master code scanning to avoid unnecessary repairs
– Use aftermarket parts when OEM prices prohibitive [7]
