
Diesel Engine Service & Repair
Fast, Reliable, and Certified Mechanics You Can Trust
Looking For Diesel Engine Service & Repair?
Trusted Diesel Specialists for Power, Performance & Reliability
Diesel engines are built for durability and power—but they also require specialized knowledge and maintenance. Whether you drive a diesel truck, SUV, or fleet vehicle, Franklynn Automotive provides expert diesel engine service and repair to keep your vehicle running strong and efficient.
Why Diesel Engines Need Specialized Care
Diesel systems are more robust than gas engines, but they rely on high compression, advanced fuel injection, and turbocharging—meaning they require experienced technicians and precise service. Ignoring maintenance can lead to reduced fuel economy, performance issues, and expensive repairs.
Signs Your Diesel Engine Needs Service
If you notice any of these symptoms, it’s time to schedule diesel diagnostics:
- Hard Starts or No Start – Often linked to glow plug or fuel delivery issues
- Excessive Exhaust Smoke – Black, blue, or white smoke indicates internal problems
- Loss of Power or Acceleration – Could point to turbo, injector, or air intake issues
- Check Engine Light or Warning Codes – Requires immediate diagnostics
- 🔊 Unusual Knocking or Engine Noise – May be due to fuel system or compression issues
- Decreased Fuel Efficiency – Dirty filters, poor timing, or injector problems
Our Diesel Engine Services
We service light and medium-duty diesel vehicles and offer:
- Diesel Engine Diagnostics – Identify fuel, turbo, emissions, and performance issues
- Fuel Injector Cleaning & Replacement – Restore efficient combustion and power
- Turbocharger Service – Diagnose and repair turbo lag or failure
- Oil & Filter Changes (Diesel Rated) – Maintain proper lubrication and prevent buildup
- Glow Plug & Ignition System Repair – Ensure reliable cold weather starting
- EGR, DPF, & Emissions Component Service – Clean or replace clogged systems for compliance and performance
- Fleet Diesel Maintenance – Priority scheduling and repair tracking for commercial vehicles
Why Choose Franklynn Automotive for Diesel Service?
- Certified Diesel Technicians – Experienced in Duramax, Cummins, Power Stroke, and more
- Advanced Diagnostic Tools – Identify complex issues quickly and accurately
- High-Quality Diesel Parts & Fluids – OEM or better for long-lasting repairs
- Transparent Communication – We explain every recommendation before work begins
- Fleet Friendly – We handle diesel fleets with efficiency and priority service

📅 Schedule Your Diesel Engine Service Today!
Keep your diesel vehicle running strong with expert diagnostics and repair from Franklynn Automotive.
Real Stories from Real Customers
See why families trust us with their vehicles
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David Brian GrayTrustindex verifies that the original source of the review is Google.
25 year old wrangler tj is running around good thanks to the guys at Franklynn Auto. Great work and not to mention reasonable prices.Posted on Google![]()
Rick GerberTrustindex verifies that the original source of the review is Google.
Steve, as usual, was very organized and ready for my appointment at 8:00 AM Monday to replace my brakes. He informed me of the changes on brakes pad composition and if I experienced any noise issues to come back and they would recheck everything. I highly recommend Franklin Automotive for all your auto service needs. Rick GerberPosted on Google![]()
Savannah LeimeisterTrustindex verifies that the original source of the review is Google.
The mechanics here are so honest and helpful! They were able to diagnose the real issue I was having with my Subaru and save me thousands of dollars I was being quoted by other shops. I would highly recommend FranklynPosted on Google![]()
Glenn MoweryTrustindex verifies that the original source of the review is Google.
This is a gem of automotive specialist from Steve Waggle on the front desk to each technician in the shop. I wish I give them all credit. For myself my focus on brake repair that has taken over a year to completely figure out. Twice at Dealer in 2 states. Towing and feeling safe since I had a failed brake master cylinder that brake upgrade was not completed on 2015 Dodge Truck. Franklyn Automotive took notes, listened, drove vehicle at my recommendation to simulate truck not being to stop. A nd Voila "they figured it out as a failed Power Braker Booster". They also did all the items on my list from premium oil changes, repair faulty wiring in Topper, tire rotation, etc, etc. Please give these folks your business. You will not be sorry. GlennPosted on Google![]()
Eben StuckyTrustindex verifies that the original source of the review is Google.
Excellent service. I woke up at 7:30, this morning, to go get some coffee; I noticed I had a screw in one of my tires. As soon as Fraklynn's opened I called and asked how long would it take for them to repair my tire. Basically they said "anytime"; it might take 60-90 minutes. I arrived at 9 a.m., I ate my breakfast in their waiting room, with my dog. I was on the road again by 9:30 a.m. The cost was affordable; i would highly recommend Franklynn Automotive.Posted on Google![]()
David RoosTrustindex verifies that the original source of the review is Google.
They performed a pre-purchase inspection for me today, on time, for a very reasonable price, and they were very pleasurable to deal with. Thank you so much, I really appreciate it.Posted on Google![]()
Greg HTrustindex verifies that the original source of the review is Google.
I have a couple vehicles that Franklynn has serviced, including a diesel pickup, and their work is always top notch and prices reasonable. They consistently fit unscheduled repairs into their calendar and the turnaround time is always exceeded regardless of the extent of the work to be performed. I would recommend them to anyone regardless of vehicle type and am grateful for their professionalism and honesty.Posted on Google![]()
Kathleen BennettTrustindex verifies that the original source of the review is Google.
Steve returned my call, scheduled a time to review my RV's problem. He estimated only 1 hour of labor plus part. This is exactly what I was billed. Steve and Bill, a mechanic, were friendly and helpful. Highly recommended. Emma BPosted on Google![]()
Ramone JeffersonTrustindex verifies that the original source of the review is Google.
I brought my 2020 VW Atlas Cross Sport to Franklynn Automotive to get a second opinion for a faulty turbo that was recently looked at by McDonald Volkswagen. I was informed by VW Service that I would need to replace my turbo and get a subsequent oil change afterwards costing $2,70000. Additionally, was charged $250.00 for the diagnostic. One of the major concerns was that the vehicle would not accelerate. I took my vehicle to get a second opinion from Franklynn Automotive who I was referred to from my wife’s best friend. Upon completion of the servicing, not only did they discover that I only had a turbo by-pass valve disconnected and a turbo hose after the intercooler hose disconnected and they did not charge me to fix this. Additionally, they changed my front and rear brakes and changed the synthetic oil for less than $800.00. This service team did phenomenal work, they also did not charge me for the initial diagnostic as well. I will be recommending them to my friends for any care service repairs and I will also become a regular customer of theirs. Satisfied customer. Ramone
Why Choose Franklynn Automotive?
ASE-Certified Mechanics – Expertise You Can Trust
At Franklynn Automotive, we take pride in the skill and professionalism of our team. Our ASE-certified mechanics are trained to the highest industry standards, ensuring that every diesel engine service & repair is done with precision and care. When you bring your vehicle to our shop, you can trust that our expert technicians have the knowledge and experience to handle everything from routine maintenance to complex repairs, keeping your car safe and reliable.


Worry-Free Repairs with Our 5-Year Local Warranty
We’re proud to back up our work with a 5-year local warranty on qualifying repairs, so you can hit the road with confidence. Whether it’s a major engine overhaul or any diesel engine service & repair, you can trust that our work will stand the test of time. At Franklynn Automotive, we believe in using quality parts and providing expert service, and our warranty proves it. When you drive away, we want you to feel secure knowing your repairs are covered.
Fast & Flexible Financing
At Franklynn Automotive, we know that keeping your car running smoothly shouldn’t break the bank. That’s why we offer fast & flexible financing options to fit your budget, whether it’s for a brake repair or replacement or larger repairs:
- NAPA EasyPay: Enjoy 6 months of promotional financing on purchases of $199 or more, and 12 months of financing on purchases of $750 or more. Keep your car in top shape today, and pay over time!
- Affirm: Choose from monthly payment plans up to 36 months, with 0% APR available. No fees or surprises—just clear, manageable payments for your auto care.



Stay on the Move While We Handle Your Diesel Engine Service & Repair
We understand that leaving your vehicle for repairs in our auto repair shop can disrupt your day. That’s why we’ve partnered with Hertz to offer our customers discounted rental rates, so you can stay on the move while your vehicle is at our shop. Whether it’s a quick fix or a more extensive repair, we’ve got you covered with affordable rental options.
Need a ride instead? We’ve also teamed up with Uber to ensure you have convenient transportation to and from our shop. Your time matters to us, and we’re committed to making your experience as hassle-free as possible.
Save More, Drive Happy
From discounts on diesel engine service to savings on bigger repairs, our deals are designed to keep you driving safely without breaking the bank. Check out our latest offers and keep an eye out for seasonal promotions to save even more!


Don’t Wait - Get Your Diesel Engine Service & Repair
Whether it’s a diesel engine service & repair or taking advantage of our flexible financing and unbeatable offers, Franklynn Automotive is here to keep you safely on the road. Our expert team is ready to help, and with our 5-year local warranty, you’ll drive away with confidence.
Call us now or schedule your appointment online! It’s fast, easy, and the first step to ensuring your vehicle’s performance and your peace of mind.
Frequently Asked Questions:
Diesel engines use compression rather than spark plugs to ignite fuel. They may also include high-pressure fuel injection, turbochargers, glow plugs and specialized emissions equipment. Diesel oil, filters, fluids and maintenance intervals must meet the engine manufacturer’s specifications. Because diesel systems operate under high pressure and tight tolerances, using the correct parts and service procedures is especially important.
Warning signs include difficult starting, loss of power, rough running, unusual knocking or whistling sounds, excessive exhaust smoke, declining fuel economy and an illuminated check-engine light. Oil, coolant or fuel leaks also require attention. These symptoms can have several causes, so diagnostic testing should be completed before fuel injectors, turbochargers or other expensive components are replaced.
Hard starting may be caused by weak batteries, faulty glow plugs, contaminated fuel, a restricted fuel filter, low fuel pressure, wiring problems or reduced engine compression. Cold Colorado mornings place additional demand on the batteries and starting system. Testing the battery, glow-plug system, fuel delivery and related controls can help identify the cause instead of assuming one component has failed.
The correct interval depends on the engine, required oil specification, operating conditions and manufacturer’s maintenance schedule. Towing, frequent idling, short trips, dusty roads and heavy-duty operation may require a different interval than normal highway driving. Diesel engines can also produce soot that enters the oil, making the correct oil and filter especially important. Follow the vehicle-specific schedule rather than applying a universal mileage rule.
Many modern diesel vehicles use diesel exhaust fluid, or DEF, as part of a selective catalytic reduction system that helps reduce nitrogen-oxide emissions. A diesel particulate filter, or DPF, captures soot from the exhaust and periodically burns it off through regeneration. These are different systems, although both are part of modern diesel emissions control. A DEF warning or DPF warning should be addressed according to the owner’s manual because ignoring it may eventually restrict vehicle operation. Ford explains the purpose of diesel exhaust fluid and its low-level warnings.
Frequent DPF regeneration can occur when the vehicle makes repeated short trips and does not remain at operating temperature long enough to complete the process. It may also indicate an engine-performance, sensor, fuel-system or emissions-system problem that is producing excessive soot or preventing successful regeneration. Continuing to command regeneration without diagnosing the underlying cause may not solve the problem.
Possible signs include reduced power, slow acceleration, abnormal whistling or grinding noises, excessive smoke, increased oil consumption or a boost-related warning code. Similar symptoms can be caused by damaged intake hoses, exhaust leaks, sensors or fuel-delivery problems. A complete diagnosis should evaluate the supporting air, oil, exhaust and electronic-control systems before the turbocharger is condemned.
Yes. Cold temperatures can increase starting difficulty, while mountain driving, towing and high engine loads create additional heat and demand. High altitude also reduces air density, although modern engine controls and turbocharging compensate for many altitude-related changes. Following the manufacturer’s severe-service recommendations, using seasonally appropriate diesel fuel and addressing warning lights promptly can support reliable operation around Littleton and throughout Colorado.
Stop driving when it is safe if the engine is overheating, oil-pressure warning appears, power drops severely, the engine runs uncontrollably, heavy smoke develops or a significant fuel, oil or coolant leak is present. A flashing check-engine light or loud mechanical noise may also indicate a condition that could worsen quickly. Contact a repair facility to determine whether the vehicle should be towed.
Franklynn Automotive provides diesel-engine maintenance, diagnostics and repair for drivers in Littleton, Highlands Ranch and nearby communities. Because equipment and parts requirements vary among diesel vehicles, customers should provide the year, make, model and engine when scheduling so the shop can confirm the requested service.