The most common Isuzu engine errors (4HK1, 6HK1, 4JJ1) – causes and solutions

Isuzu engines are famous for their reliability, durability and economy. Isuzu diesel engines, in particular the 4HK1, 6HK1 and 4JJ1 models, are widely used in special equipment: construction, quarrying, mining, logging and other equipment. However, sometimes, like any power units, they can fail over time. Let's look at the most common errors and malfunctions of Isuzu engines, and how to effectively fix the malfunctions.

Error P0401 - insufficient flow in the EGR system

Possible problem: EGR valve malfunction or clogging

What it looks like: the appearance of black smoke, Check Engine or partial or complete loss of traction.

Decision: cleaning or replacing the EGR valve and thoroughly checking the vacuum system

Error P0200 - problem with the fuel injection system and injectors

Possible problem: short circuit or break in the injector wiring

What it looks like: unstable engine operation, possible stalling when pressing the gas

Solution: injector and system diagnostics, replacement of faulty injector

Error P0217 - engine overheating: one of the most common and dangerous errors

The following codes may also appear:

• P0217 — Engine Over Temperature Condition (Engine Overheating)
• P0117 — Engine Coolant Temperature Circuit Low Input (Low signal from the coolant temperature sensor)
• P0118 — Engine Coolant Temperature Circuit High Input
• P0128 — Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature) Low coolant temperature — thermostat does not reach operating temperature

What it looks like:

• the temperature needle on the instrument panel enters the red zone, or approaches the maximum
• engine power is reduced (derate mode), the ECU automatically limits power to prevent damage
• possible activation of emergency mode (Check Engine) or (High Coolant Temp)
• possible stains under the equipment, or a sharp decrease in the coolant level in the tank caused by coolant leakage
• due to a thermal imbalance, the engine may stall or run unevenly
• Steam or smoke may appear from under the hood - usually from the radiator, hoses, or expansion tank cap
• Solution: urgent check of coolant level and condition (only after engine has cooled)
• check for traces of oil in the antifreeze: if there are such traces, this may indicate damage to the cylinder head gasket
• assessment of the radiator condition: cleaning, flushing if necessary (if it looks like internal contamination)
• Check the fan/viscous coupling: the coupling should rotate freely when the engine is hot. Replace if necessary.
• Evaluation of the thermostat: after starting the engine, one pipe will be warm, the other cold until the thermostat itself opens (80-85 degrees). If one of the pipes remains cold, the thermostat is most likely stuck and needs to be replaced.
• check the cylinder head and system pressure: the presence of bubbles in the expansion tank with the engine running, and if the CO₂ test shows the presence of carbon dioxide in the cooling system - the cylinder head gasket needs to be replaced

Also additionally:

• avoid running the engine at high rpm until the problem is resolved
• check the tension of the cooling pump belt (if mechanical)

Error P0335 – Crankshaft Position Sensor

Problem: signal outline or sensor failure

What it looks like: the engine stalls or does not start

Decision: thorough inspection of the wiring and, if necessary, replacement of the sensor.

General tips:

• regularly replace oil, air and fuel filters
• perform diagnostics via OBD2 or dealer scanner
• after the Check Engine appears, in no case do not delay with repairs
• use only original or high-quality licensed spare parts

Isuzu engines such as the 4HK1, 6HK1, and 4JJ1 can last for many years if properly maintained. Timely diagnostics and quality repairs will help avoid serious breakdowns and keep your equipment in working condition.

If you need spare parts for Isuzu engines, contact us – we will help you quickly find what you need!