### P0420 Catalyst System Efficiency Below Threshold

– Common Causes:

Worn catalytic converter [1]

– Suggested Repairs:

Diagnose fuel trim https://carautorepair.site/

### P0171 Air-Fuel Ratio Error

– Potential Issues:

Faulty MAF sensor

– Testing Procedure:

Check fuel pressure [1][7]

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## Auto Repair Terminology

### Electronic Braking System

– Function: Enables safe braking [7]

### Engine Management Unit

– Role: Controls ignition timing [7]

### Drivetrain Components

– Contains: Drive axles [7]

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## Repair Process Steps

1. **Symptom Assessment**:

Scan DTCs

2. **Part Evaluation**:

Check voltage

3. **Component Installation**:

Use OEM parts

4. **Post-Repair Verification**:

Ensure proper operation

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## Critical Instruments

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

|—|—|—|

| Code Reader | BlueDriver | Retrieve DTCs |

| Physical Equipment | Multimeter | Component repair |

—

## Service Information References

### Mechanical Information System

– Features:

Component locations [8]

Technical illustrations

### Digital Assistants

– Vehicle Service App:

ECU pinouts [5]

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## Budget Repair Strategies

– Regular maintenance prevents major failures

– Understand DTC meanings to prevent mechanic overselling

– Use aftermarket parts when OEM prices prohibitive [7]