Top 5 Common Fault Codes in Commercial Trucks and How to Fix Them

Introduction

Fleet managers and truck technicians encounter the same fault codes repeatedly. Here are the top 5 most common ones and how to address them.

1. P0401 – EGR Flow Insufficient

The Exhaust Gas Recirculation valve is often clogged with carbon deposits. Clean or replace the EGR valve and retest.

2. P1093 – Fuel Rail Pressure Low

This often indicates a failing high-pressure fuel pump or clogged fuel filter. Check fuel pressure with a diagnostic tool before replacing parts.

3. P0087 – Fuel System Pressure Too Low