Diagnosing Low Oil Pressure in Semi Trucks

Recently updated on June 12th, 2025

Your oil pressure is a vital sign that your semi-truck is performing optimally and should be something you are constantly monitoring in your travels. Low oil pressure can lead to a number of different problems that can range from minor hiccups to catastrophic issues that can damage your engine. Knowing how important good oil pressure is can help you recognize a problem before it arises, and knowing how to diagnose low oil pressure can save you time, money, and more costly issues on the road.

Proper oil pressure isn’t a “nice to have” in a semi-truck: it’s absolutely critical for keeping your engine in great working condition. With the right oil pressure, all of the moving parts in your engine are well-lubricated without building up friction and suffering from excessive wear and tear. When your oil pressure drops, your engine components aren’t getting the correct amount of oil and lubrication, which can cause serious problems for your vehicle’s reliability and safety.

In this guide, we’ll bring you through a primer on oil pressure, including the risks of low oil pressure, different symptoms that you should be able to recognize, and a step-by-step diagnostic process that should be able to help you get an idea of potential issues. We’ll also go over the necessary tools for the job, as well as different common issues and their solutions.

One of the most important things to keep in mind while reading through this guide is that it’s just as important to know when to call the professionals as it is to know how to diagnose and address these issues.

If you are dealing with low oil pressure, don’t forget that LubeZone has locations all across the country, and we’re here to help you keep your semi-truck in excellent condition for miles and miles to come. Visit your nearest LubeZone location today for professional oil pressure diagnostics and services.

Understanding the Risks of Low Oil Pressure

Low oil pressure can create a wide range of problems that may show up as small inconveniences just as easily as they may show up as catastrophic engine failures. Even low oil pressure that doesn’t cause permanent damage will lead to poor engine performance, worse fuel economy, and, if left uncorrected, serious and costly damage to your engine. The following are just a few of the major issues you can encounter with unchecked low oil pressure:

Engine Damage

When your oil isn’t able to effectively lubricate all of the moving parts of your engine, the friction between the parts increases, and they start to directly grind against each other. When moving parts are grinding against each other, wear and tear accelerates as the engine temp steadily rises, and ultimately, the engine fails. Ignoring low oil pressure can quickly lead to catastrophic damage that may even require a complete engine replacement, a significant expense that comes with major downtime.

Reduced Fuel Efficiency

We’ve already talked about what happens to the machinery when your engine doesn’t have proper oil pressure, but in addition to the friction buildup and increased wear, it requires more power to move the inner components of the engine through the added friction. Even moderate low pressure that won’t cause immediate damage to your engine will increase the force required to keep the engine moving, which will reduce your fuel efficiency. If you notice that you are starting to lose efficiency, your oil pressure might be something to take a look at.

Increased Maintenance Costs

Sometimes, ignoring low oil pressure isn’t an option, but sometimes you can let it slide — not something we’d recommend. When you ignore your low oil pressure, you are directly contributing to higher maintenance costs as engine components begin to wear out and fail. Beyond the wear and tear, there is also the very real threat of a major breakdown or engine failure while you are out on the road, leading to late deliveries, tow costs, emergency repairs, and ongoing lost income due to your unexpected downtime.

Recognizing the Symptoms

Luckily, there will be early signs that may indicate you are having some oil pressure issues. If you notice any of these issues, it’s a good idea to get off the road as soon as possible and do some diagnostics before you power through and cause catastrophic damage to your engine.

Warning Lights

One of the first signs of a problem with your oil pressure is the oil pressure warning light. It’s also the most obvious because, well, it’s a warning light for just that thing! The light will activate if your oil pressure either falls below or exceeds a certain threshold. Ignoring the light is a bad idea because this is your early warning sign that there is trouble. The first thing to do is to pull over, let your engine cool a bit, and then check your oil level. If the oil level is in the right range, then it might be a sign that your oil pump or pressure sensor is having issues, both of which need a diagnostic from a professional service center like LubeZone.

Engine Noise

Noises coming from your engine are never good signs and can indicate all sorts of issues, not just low oil pressure. But if you are hearing knocking, ticks, or clattering, it could be a sign that your engine components aren’t getting the right lubrication, and what you are hearing might be the moving parts of your engine rubbing against each other without a protective layer of oil. Knocking is usually a sign that the bearings in your engine are being damaged, while ticking might mean that the valve train is having issues. It’s almost impossible to diagnose an engine issue based solely on the sound it is making, so get your truck into a service center ASAP to get it on a lift and properly diagnosed.

Poor Engine Performance

Naturally, insufficient oil delivery to your engine will result in diminished engine performance. If you feel like your truck isn’t accelerating as it should, the power output is lacking, or you are having a hard time maintaining your speed in consistent conditions, then the issue could be with your oil pressure. Again, this all comes back to friction buildup in the engine because the components aren’t properly lubricated and are losing efficiency as they build up heat and scrape against each other. If you have a noticeable, drastic drop in performance, one of the things you should be exploring is your oil pressure. Start by checking your oil levels to make sure that you aren’t out of oil.

Comprehensive Diagnostic Guide

Here is a comprehensive guide for doing your own roadside diagnostics, but it requires more than know-how. You need to knowledge and the tools to make sure that you can perform some basic field diagnostics, but remember that this is ultimately a task that is best handled by professionals. These steps will help you keep your truck safe on the road and help you make a determination about what next steps to take, but they should never replace the diagnostics that a comprehensive service center can offer.

Tools Required for Oil Pressure Diagnosis

We already discussed how the sounds your engine is making can give you an idea of the issue, but to make a complete diagnosis, you’ll need some tools. Here are the main tools you’ll need for the process:

• Oil Pressure Gauge: This gauge will help accurately measure the oil pressure in your engine
• Wrenches and Sockets: It’s always a good idea to keep a full wrench and socket set in your truck.
• Oil Filter Wrench: This specialized tool grips the oil filter and helps it come off more easily without causing damage.
• Safety Gear: Gloves, safety glasses, and protective coveralls are all very important while you are diagnosing your oil pressure issues.

Checking Oil Pressure

1. Warm Up the Engine: Start the truck and let it run for a bit to bring it up to the normal operating temperature. If you have already been running your truck, let it cool down a bit before getting started.
2. Locate the Oil Pressure Port: You can refer to the manufacturer’s manual to find the exact location for your engine model, but it’s typically found on the engine block.
3. Attach the Oil Pressure Gauge: Screw the gauge into the port and make sure that it’s completely secured.
4. Read the Gauge: Once you have the gauge connected, and while the engine is running, get a reading and compare it to the manufacturer’s recommended oil pressure specifications.
5. Make a Plan of Action: If your pressure is below the optimal range, you need to take further steps to look for the cause.

Common Oil Pressure Problems and Solutions

Problem: Low Oil Pressure Readings

If you checked your oil pressure and you are getting a low reading, there are a few steps to take right off the bat.

1. Check for Oil Leaks: If you see any visible leaks around your engine, this could be a good candidate for why your oil pressure is dropping.
2. Inspect Your Oil Level: If your oil level is low and you aren’t having leaks, this could be another reason why your pressure is low.
3. Check the Oil Quality: If your oil is old or degraded, it may be impacting the oil pressure. If your oil is dirty or you are late on getting an oil change, this could be a sign to get into LubeZone right away.

Solution: Low Oil Pressure Readings

1. Fix Leaks: Identify the cause of the leaks and fix them as soon as possible.
2. Top Up Oil: If your oil is low and you don’t have a leak, top up and see if that changes your pressure readings.
3. Oil Change: Getting your oil changed is a chance to resolve an issue caused by old oil, and also gives techs a chance to get a closer look at your engine to look for other issues that could be impacting your oil pressure.

Problem: Clogged or Dirty Oil Filter

1. Set Up an Oil Pan: Before you remove your oil filter, make sure you have a pan underneath to catch the oil that runs out.
2. Remove the Oil Filter: Using an oil filter wrench, unscrew the filter and remove it.
3. Inspect the Filter: Look for clogging, contamination, or other problems that could disrupt the flow of oil through your system.

Solution: Clogged or Dirty Oil Filter

1. Replace the Filter: If your filter is clogged or dirty, it’s time to replace it. This should be done at the same time as an oil change. Even though some filters can be cleaned and reused, they are most often replaced outright.
2. Keep Up With Your Oil Changes: It’s a good idea to stay on a schedule for oil changes to avoid issues like clogged oil filters, low oil levels, and other issues that can be avoided with routine maintenance.

Problem: Oil Pump Failure

1. Listen for Noises: It sounds like grinding or knocking might be a sign that your oil pump is failing or has failed completely.
2. Check for Leaks: If you see leaks in the area around your oil pump, this might be another sign that it has failed.
3. Assess Oil Flow: If you have the tools and knowledge, you can check your oil flow rate, but this is best left to the professionals.

Solution: Oil Pump Failure

1. Replace the Oil Pump: If your oil pump is starting to struggle or has completely failed, it’s time for a replacement. Don’t ignore it because once it fails, you’ll end up on the side of the highway, and your delivery schedule will be disrupted.
2. Regular Inspections: Routine inspections and maintenance are key to making sure that any potential issues are recognized early and taken care of before they turn into emergencies. This is something that happens during oil changes.

When To Call the Professionals

It’s essential to have some basic troubleshooting skills in your back pocket so you can resolve, or at least identify, various oil pressure issues. However, there are times when you need to call in professionals, such as the technicians at LubeZone. If you are having persistent pressure issues after addressing the common issues, your oil light won’t turn off, or your truck is making some bizarre sounds, it’s probably time to get your truck in for a comprehensive diagnostic exam.

Repairs such as oil pump replacements, damaged crankshafts, or internal engine repairs should be left to professionals to ensure you aren’t making costly mistakes or causing further damage.

Getting regular oil changes and routine maintenance from LubeZone can give you an advantage by recognizing potential issues before they are bad enough to take you off the road. Noticing an oil pump issue before it fails is typically much less expensive and means you can schedule the repair into your schedule instead of needing to take unexpected downtime that disrupts your customers’ schedules, costs you lost income, and decreases your customer satisfaction.

LubeZone

LubeZone is the fastest growing dedicated semi-truck service in the United States with locations in Texas, California, Oklahoma, North Carolina and Georgia. Our preventative maintenance solutions are designed to get the professional driver back on the road FAST.