← View Generic P0428 Guide Severity: Medium

🚗 Vehicle-Specific Guide

This guide is customized for your 2021 Honda PASSPORT

P0428: P0428: Catalytic Converter Efficiency Below Threshold

on 2021 Honda PASSPORT

Fix Cost

$200 - $1000

Parts & Labor

Difficulty

3/5

1-2 hours

DIY Possible?

❌ No

Pro recommended

Your Vehicle

2021 Honda

PASSPORT

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Important for 2021 Honda PASSPORT Owners

Before starting repairs, verify which engine your 2021 Honda PASSPORT has. Check your VIN or engine code to ensure you order the correct parts.

📖 What Does P0428 Mean on 2021 Honda PASSPORT?

The catalytic converter is not functioning within normal parameters, which can cause excessive emissions and decreased fuel efficiency.

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Symptoms

• Rough idling
• decreased fuel efficiency
• increased emissions
• and a check engine light.

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Common Causes

• Clogged or dirty catalytic converter
• faulty oxygen sensor
• or a vacuum leak.

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How to Fix P0428 on 2021 Honda PASSPORT

1. Inspect and clean the catalytic converter. 2. Replace the oxygen sensor if faulty. 3. Repair or replace the vacuum leak.

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Need Maintenance Info for Your PASSPORT?

Get oil capacity, filter specs, and torque settings for your specific 2021 Honda PASSPORT.

View 2021 Honda PASSPORT Specs

Parts for 2021 Honda PASSPORT

catalytic converter Shop ↗ oxygen sensor Shop ↗

Essential Tool

Must Have

OBD2 Scanner

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Related Diagnostic Codes

Other codes that may appear with P0428

P0426 Sequential Code

💡 Why These Codes Are Related:

• Similar Issues: Same root cause or component failure
• Related Problems: Often occur together due to system interactions
• Sequential Codes: Progressive failure stages or multiple sensors
• Same System: Components within the same automotive system