Common Diesel Fault Codes

These fault codes relate to the high-pressure fuel circuit: the rail, suction control valve, pressure relief valve, and fuel pump. They are among the most common fault codes on modern common rail diesel engines and are frequently misdiagnosed.

P0088 Fault Code: High Fuel Rail Pressure Guide

P0088 code means fuel rail pressure is too high. Learn what causes pressure spikes and how to diagnose the issue correctly.

Fault P0093: Fuel System Large Leak Detected

P0093 fault code points to a drop in fuel rail pressure inside the system. Understand what triggers it and how to pinpoint the real cause.

The P1089 fault code usually means the fuel rail pressure is off, but the pump often isn’t to blame. Check injector leak-back and relief valve first.

These fault codes relate to turbocharger boost control, VNT vane operation, and the electronic actuators that manage them. Turbo-related codes are common on variable geometry turbo systems and are frequently triggered by modifications, carbon buildup, or actuator wear rather than turbo failure itself.

P0046 — Turbo Boost Control Solenoid Circuit Range/Performance

P0046 fault code can lead to low boost, poor performance, and engine issues. Get clear insight into causes and solutions.

P1251 — Turbo Overboosting (Toyota Hilux)

P1251 Toyota fault code points to turbo overboost on Hilux diesels. Learn causes, symptoms, and how to diagnose and fix it properly.

These codes relate directly to the fuel injectors, their wiring, and the ECM circuits that control them. Injector-related faults are common on high-kilometre common rail diesel engines and range from simple wiring faults to worn or leaking injectors requiring replacement.

P0200 — Injector Circuit Malfunction

P0200 can lead to engine misfires, poor fuel economy, and stalling. Find out what’s behind the injector circuit fault.

EGR fault codes relate to the exhaust gas recirculation system, which controls combustion temperatures and NOx emissions. Carbon buildup is the dominant cause on most diesel engines.

P0400 — EGR Insufficient Flow / Malfunction

P0400 fault can lead to rough idle, knocking, and poor fuel economy. In this blog, you will learn about EGR system issues and find out how to diagnose them.

Beyond individual fault codes, the following guides cover broader diagnostic topics that are frequently relevant when fault codes appear.

Diagnosing Common Rail Diesel Faults — The Suction Control Valve

Driveability issues or limp mode? A worn suction control valve could be the problem. Learn how to diagnose it.

HELP! I Can't Code My Injectors

What happens if you don’t code injectors? In this blog, find out how it leads to power loss, engine damage, and poor fuel control in diesel engines.

Euro 5 Hilux / Prado — Fault Code P1601

After installing 295050-0460 injectors in your Toyota Hilux or Prado, you might see code P1601. Here's how to resolve it step-by-step.

1KD-FTV Injector Diagnosis — Cold Knock and Wear

Cold knock and high correction values in 1KD engines can signal injector failure. Learn how to diagnose issues before they cause major engine damage.

Nissan Navara White Smoke and No-Start

Tons of white smoke and a non-starting Navara? A failed EGR valve may be the cause. Learn how to test and fix it.