Has your diesel engine just not been performing like it used to? Maybe you’ve noticed a drop in fuel economy, or other new issues. There’s a chance that you might need to replace your common rail injectors.
These vital components are key to a properly functioning engine, ensuring that the combustion process happens as it should. If they aren’t working right, you’re going to notice a change in the way your engine performs.
So, is it time to replace those injectors? We’re taking you through some of the symptoms you should know!
For more information on replacing common rail fuel injectors, be sure to check out our video:
Do you need replacement parts for your diesel engine? Our ASE Certified Technicians can help you find what you’re looking for!
When is it Time to Replace Your Common Rail Injectors?
You’re probably wondering just how you know when to replace your injectors. Here are a few things that can indicate it might be time to have your common rail injectors looked at.
One symptom you might notice right away is poor fuel efficiency. You might also see blue smoke coming out of your exhaust.
If you smell raw fuel coming out of your exhaust, it’s time to have your injectors checked.
Have you ever noticed fuel in your oil? If so, you might want to take a look at your injectors. This is because you have the potential for excess fuel to get into your cylinders, and then dropping down into your crankcase. It can also cause return leaks, if it’s underneath the valve cover, getting into your crank that way.
Engine misfires can be a clear sign that you need to replace your diesel injectors as well. You can have one or two cylinders down, or it can just be a wiring harness as well, but it’s always something to check.
If you’re looking for new injectors for your diesel engine, but aren’t sure where to start, check out our article on choosing the right injectors for you!
How Often Should Diesel Injectors Be Replaced?
If you’re purchasing a good-quality fuel injector, it should last you around 95,000 miles. We recommend having a professional inspect your injectors once you hit that mark to verify their condition. For optimal injector performance, don’t ignore any warning signs, and make sure to use high-quality fuel!
What Should You Do About Failed Common Rail Injectors
So just what should you do if you have a failing common rail injector system?
If you have any of these symptoms, you should have your vehicle scanned, if it’s possible. Have your injectors sent in for testing at a certified location.
Doing this can help you to diagnose exactly what’s going on in your diesel engine, and help you to not only fix the problem now, but to better understand what went wrong, so you can help prevent it from being an issue again.
If you find that you need new injectors, Highway & Heavy Parts can help! We have a great selection of replacement injectors for your diesel engine. Our on-staff ASE Certified Technicians can help make sure you’re getting the right injectors for your application. Having your engine serial number on hand can help make sure you get the right parts the first time you order, and it can speed up the ordering process.
Want to know no more about the causes of fuel injector failure? Read our post, Diesel Engine Common Rail Injectors: Potential Failures & Causes.
In need of replacement injectors for your diesel engine? We have ASE Certified Technicians on staff who can make sure you get the right fit for your engine! Call us at 844-304-7688, or request a quote online!
FAQs for “How Do You Know When It’s Time to Replace Your Diesel Engine Fuel Injectors”
1. What are the early warning signs that my diesel engine injectors need replacement?
Look for hard starting or extended cranking, rough or uneven idle, noticeable misfire or cylinder cut‑out, excessive black or white smoke under load, fuel odor in the crankcase, and a sudden drop in fuel economy. Metal filings in the fuel filter or oil pan also indicate internal injector wear and bearing debris.
2. How does a failing injector affect overall engine performance and fuel efficiency?
A worn or leaking injector delivers uneven or excessive fuel leading to poor atomization. This causes incomplete combustion, which increases soot and unburned fuel, raising exhaust emissions and fuel consumption. You may experience loss of low‑end torque, hesitation on acceleration, higher EGTs (exhaust gas temperatures), and rapid fuel filter clogging.
3. How can I diagnose a bad injector before it causes major engine damage?
Perform a cylinder balance or power balance test with a scan tool to identify cylinders dropping out. Listen with a long screwdriver or use an in‑line stethoscope for uneven injector noise. Check injector electrical resistance with a multimeter against manufacturer spec. Finally, monitor injector return flow and compare balance rates; a deviation over 4 mm³/stroke indicates a weak or leaking injector.
4. What common factors cause diesel injector failure?
Contaminated fuel with water or particulates scores nozzle and needle, causing poor spray pattern. Extended idling at low load leads to carbon buildup and glaze on injector tips. High‑pressure pump anomalies or thermal shock from abrupt cool‑down also crack injector bodies. Using incorrect fuel additives or skipped filter changes speeds wear and corrosion.
5. What maintenance practices can extend the life of my diesel injectors?
Change primary and secondary fuel filters per OEM intervals (typically every 10 000–15 000 miles). Use high‑quality, low‑sulfur diesel and a reputable anti‑gel additive in cold climates. After heavy load or hard driving, let the engine idle 30–60 seconds before shutdown to cool and flush injectors. Periodically run a professional injector cleaning service and inspect return lines for leaks.
