## Common Diagnostic Trouble Codes

### P0420 Catalyst System Efficiency Below Threshold

– Typical Sources:

Faulty oxygen sensor [1]

– Recommended Fixes:

Diagnose fuel trim https://carautorepair.site/

### P0171 Air-Fuel Ratio Error

– Potential Issues:

Vacuum leaks

– Diagnostic Steps:

Check fuel pressure [1][7]

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## Auto Repair Terminology

### ABS (Anti-Lock Brake System)

– Purpose: Prevents wheel lockup [7]

### ECM/ECU (Engine Control Module)

– Responsibility: Monitors sensors [7]

### Powertrain Elements

– Contains: Transmission [7]

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## Mechanical Fixing Workflow

1. **Initial Diagnosis**:

Perform visual inspection

2. **System Verification**:

Measure resistance

3. **Defective Unit Swap**:

Clear error codes

4. **System Validation**:

Confirm warning light reset

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## Necessary Equipment

| **Tool Type** | **Examples** | **Purpose** |

|—|—|—|

| OBD-II Tool | BlueDriver | Retrieve DTCs |

| Mechanical Tools | Smoke machine | Electrical testing |

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## Repair Documentation Sources

### Vehicle Service Database

– Capabilities:

Wiring diagrams [8]

Factory repair procedures

### Smartphone Tools

– Vehicle Service App:

Electrical diagrams [5]

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## Affordable Maintenance Advice

– Preventative service avoids costly repairs

– Master code scanning to avoid unnecessary repairs

– Use aftermarket parts when OEM prices prohibitive [7]