### P0420 Catalyst System Efficiency Below Threshold
– Common Causes:
Faulty oxygen sensor [1]
– Common Solutions:
Replace catalytic converter 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
– Responsibility: Monitors sensors [7]
### Powertrain Elements
– Contains: Differential [7]
—
## Repair Process Steps
1. **Initial Diagnosis**:
Scan DTCs
2. **Part Evaluation**:
Check voltage
3. **Parts Replacement**:
Clear error codes
4. **Final Quality Check**:
Confirm warning light reset
—
## Critical Instruments
| **Tool Type** | **Examples** | **Purpose** |
|—|—|—|
| Code Reader | Autel | Retrieve DTCs |
| Hand Instruments | Multimeter | Component repair |
—
## Service Information References
### Vehicle Service Database
– Capabilities:
TSB access [8]
OEM specifications
### Smartphone Tools
– Vehicle Service App:
Electrical diagrams [5]
—
## Affordable Maintenance Advice
– Preventative service prevents major failures
– Understand DTC meanings to prevent mechanic overselling
– Use aftermarket parts when budget constrained [7]