Common Diesel Engine Problems and How to Fix Them

Common Diesel Engine Problems and How to Fix Them

Driving your vehicle smoothly from one place to another is what we all want. Just like the human heart, your vehicle’s diesel engines control your vehicle’s movement. Sometimes, your diesel engine can have unusual problems that affect its performance or cause them to stop working. 

This can be frustrating when you’re unsure of what’s causing the issue. Ignoring diesel engine problems can make them worse and more costly to fix. If you can figure out what caused the issue, then you can take action. But for complex cases, it’s better to call a diesel mechanic.

Regular diesel engine maintenance keeps your vehicle running smoothly. In this article, we’ll show you some common diesel engine problems, how to diagnose them, and how to fix them. We’ll also tell you how to prevent these problems from happening.

Let’s drive through!

Diesel Engine Problems: Diagnosis, Solutions, and Preventative Measures

Diesel engine problems can ruin your good mood and if ignored can cause your engine to break down. Our engineers have listed some common diesel engine problems, their diagnosis, solutions, and preventative measures to help you maintain your good mood.

1. Diesel Engine misfire 

Your diesel engine can misfire when one or more cylinders in the diesel engine fail to ignite properly. This causes your diesel engine to run rough or sluggish and can sometimes lose power. 


These are what can cause your diesel engine to misfire:

  • Faulty spark plugs. 
  • Ignition system issues.
  • Fuel system problems.
  • Clogged fuel injectors.


Let’s show you what to look out for if your diesel engine misfires.

  • Check for worn-out spark plugs and damaged wires.
  • Check for damaged ignition coils. 
  • Check your fuel pressure and flow rate.
  • Inspect your fuel injectors for clogs or damage


Here are possible solutions if your diesel engine misfires:

  • Replace your worn-out spark plugs. 
  • Changing your ignition coils can help restore your diesel engine’s performance.
  • Cleaning or replacing your fuel injectors can help in solving the problem
  • Changing or cleaning your faulty fuel pump can restore proper fuel flow and improve your diesel engine performance.

Preventative measures 

Here are some ways to prevent diesel engine misfires and keep it running at its best.

  • Conducting regular maintenance such as oil changes, air filter replacements, and fuel system cleanings. 
  • Ensure you use only high-quality fuel.
  • Replace your spark plugs at regular intervals (usually every 30,000 miles). 
  • Replacing your ignition coil at the first sign of failure can help prevent further damage to the diesel engine.

It’s best to contact a mechanic to conduct routine maintenance on your diesel engine to keep it operational when needed.

2. Overheating 

Overheating can reduce your diesel engine’s performance, fuel efficiency, and increase emissions. Let’s show you its causes, diagnosis, solution, and preventative measures.


Here are some of the causes of overheating.

  • Low or leaking coolant 
  • Faulty thermostat and water pump 
  • Clogged or blocked radiator 
  • Faulty radiator fan


These are what to look out for if your diesel engine overheats:

  • Check your coolant level or for loss of coolant 
  • Inspect your thermostat for faults
  • Check your water pump for damage
  • Check your radiator fan for faults


Now here’s what you can do if your diesel engine overheats: 

  • You can turn off your vehicle and let the diesel engine cool down.
  • Check and add coolant if it’s low.
  • If your radiator, water pump, or hoses are leaking, try replacing them or call a mechanic.
  • If your thermostat is faulty, replace it.
  • Ensure that your radiator fan is functioning properly.

Have a professional mechanic diagnose and repair any underlying issues causing the overheating

Preventative measures 

To prevent overheating, do this:

  • Regularly check and maintain your coolant level and quality.
  • Flush and refill your cooling system as instructed by the manufacturer
  • If your thermostat, hoses, belts, and water pump are worn out, replace them as recommended by the manufacturer.
  • Check your radiator and keep it clean and clear of debris.

It is important to monitor your diesel engine’s temperature and contact a professional mechanic to prevent your diesel engine from failing. 

3. Rough Idling 

Rough idling is that noticeable roughness or a lumpy idle, that causes your vehicle to shake or vibrate. It can also cause your diesel engine to stall or hesitate when accelerating from a stop. 


These are some causes of rough idling:

  • Vacuum leaks 
  • Dirty air filter 
  • Faulty idle air control valve 
  • Low fuel pressure


We’ve listed out some things you should look out for here:

  • Check for leakages in your vacuum system 
  • Inspect your air filters for dirt
  • Check your idle air control valve for faults 
  • Check if your fuel pressure is low 


Here’s what you can do:

  • If there’s a leakage in your vacuum system contact a mechanic to fix or replace it.
  • If there is dirt in your air filters, ensure you remove them.
  • Replace your idle control valve if they are faulty.
  • Replace your fuel pressure regulator if they are faulty

Preventative measures 

There are many ways to prevent this, some of them are:

  • Contact a mechanic to perform routine checks on your diesel engine’s vacuum system.  
  • Cleaning your air filters regularly to prevent clogging.
  • Replace your idle air control valves when necessary. 
  • Ensure you use only high-quality fuel.

4. Electrical fault

If your diesel engine fails to start or runs poorly, there’s a chance that it’s an electrical fault. This would require you to contact a professional mechanic as electrical faults are dangerous.


There are many reasons for electrical faults in your diesel engine. We’ve listed some of them for you.

  • Dead battery 
  • Faulty alternators 
  • Damaged electrical wire or blown fuse 
  • Bad spark plugs and spark plug wires


Here’s what you should look out for:

  • Check if your battery power has depleted 
  • Inspect your alternator for fault
  • Look for damaged wires or blown fuse 
  • Check for faulty spark plugs or damaged spark plug wires


Here’s what you can do:

  • If your vehicle  battery is depleted, you can revive it by jump-starting or recharging it. 
  • Change your alternator if it is faulty.
  • If you see a blown fuse or faulty spark plugs, try replacing them.
  • For damaged spark plug wires it’s best to contact a professional to avoid getting electrocuted.

Preventative measures

Electric faults can occur occasionally. Here’s what you can do to prevent some of these issues:

  • If your battery has reached the end of its lifecycle, it’s wise to change it immediately.
  • When conducting routine maintenance, check your alternator, fuse, and spark plugs. Try replacing them when necessary.
  • Take your vehicle to the mechanic for regular maintenance. They’d notice when there’s a loose or faulty wire and fix it immediately.

A Word From an Diesel Engine Specialist

Diesel engine problems can escalate if they are not fixed immediately. If you notice an unusual sound or problem from your diesel engine, turn it off instantly to prevent escalation. Then check if it’s something you can fix, else call a mechanic quickly.

If you reside in Arizona, Phoenix Diesel Repair is the best choice for you. We have maintained our top-notch quality services in diesel engine repairs for 25 years. Our goal has always been to exceed our customer’s expectations. We are quick, professional, and pocket-friendly. Let’s keep your diesel engine running smoothly in no time. Reach out to us.

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