QDC Auto Repair

07/17/2026

🚨 Diesel fuel and DEF should never mix.
This photo shows the inside of a diesel injection pump after Diesel Exhaust Fluid (DEF) was accidentally poured into the fuel tank. Those white crystals aren’t dirt—they’re crystallized DEF, and they can quickly destroy a diesel fuel system.
Unlike diesel fuel, DEF is a water and urea-based solution. When it enters the fuel system, it crystallizes inside critical components like the injection pump, fuel injectors, fuel rails, lines, and filters. Once that happens, the contamination spreads throughout the entire system.
Unfortunately, if the engine has been started after DEF contamination, the repair is rarely as simple as draining the tank. In many cases, it requires replacing the injection pump, injectors, fuel rails, fuel lines, filters, and thoroughly cleaning the entire fuel system.
If you accidentally put DEF in your diesel fuel tank:
❌ Do not start the engine.
🚗 Have the vehicle towed to a repair facility immediately.
Turning the key and allowing the fuel system to circulate contaminated fuel can turn a relatively simple mistake into a repair costing thousands of dollars.
At QDC Auto Repair, we have the equipment and experience to properly diagnose and repair diesel fuel system contamination so your truck can get back on the road.
📍 QDC Auto Repair
11812 N Tangerine Business Loop
Marana, AZ
📞 520-395-0435
Diesel diagnostics done right. Honest repairs. Quality workmanship. 🔧

07/16/2026

🔍 Not every oil leak is easy to find—but that’s where proper diagnostics make the difference.
This vehicle came in with an engine oil leak that wasn’t obvious during a visual inspection. To accurately locate the source, we added UV dye to the engine oil and allowed the engine to run. Using a UV light, we were able to trace the glowing dye directly to the source of the leak—a failed rear main seal.
The rear main seal sits between the engine and transmission, making it one of the more difficult leaks to diagnose and repair. Without proper testing, it’s easy to mistake it for an oil pan gasket, valve cover leak, or another nearby oil leak.
That’s why we don’t guess—we test.
Using UV dye allows us to pinpoint even the smallest leaks, ensuring our customers only pay for the repair that’s actually needed.
If you’ve noticed oil spots in your driveway or your vehicle is losing oil but you can’t see where it’s coming from, let us find the source before it turns into a bigger problem.
📍 QDC Auto Repair
11812 N Tangerine Business Loop
Marana, AZ
📞 520-395-0435
Honest diagnostics. Accurate repairs. Done right the first time. 🔧

07/14/2026

⛽ Is your fuel gauge acting up? The problem might not be the fuel level sensor itself.
This vehicle came in with an inaccurate and inconsistent fuel gauge. After removing the fuel pump assembly from the tank, we found the real problem—the fuel pump assembly had come apart internally.
Because the assembly was no longer secured together, it was moving around inside the fuel tank. As it shifted, the fuel level sensor couldn’t accurately track the fuel level, causing the gauge to jump around and display incorrect readings.
Symptoms of a failed fuel pump assembly can include:
⛽ Fuel gauge reading incorrectly or changing randomly
⚠️ Running out of fuel even though the gauge shows fuel remaining
🚗 Intermittent fuel level readings after filling up
🔧 Check engine light related to the EVAP or fuel system
This is a perfect example of why proper diagnostics matter. It’s easy to assume the fuel level sensor has failed, but in this case, the real issue was a broken fuel pump assembly.
At QDC Auto Repair, we take the time to diagnose the root cause so you only replace what’s actually needed.
📍 QDC Auto Repair
11812 N Tangerine Business Loop
Marana, AZ
📞 520-395-0435
Quality diagnostics. Honest repairs. Done right the first time. 🔧

07/10/2026

07/07/2026

🚛 Loss of power? Frequent regens? Check engine light on? It could be your DPF.
This Ram Cummins came into the shop with a severely clogged Diesel Particulate Filter (DPF). Over time, soot builds up inside the filter, restricting exhaust flow and making it harder for the engine to breathe.
A clogged DPF can cause:
• 🚨 Check engine light or DPF warning light
• 💨 Loss of power and sluggish acceleration
• ⛽ Reduced fuel economy
• 🔄 Constant regeneration cycles
• ⚠️ Limp mode if the restriction becomes severe
The photo shows just how plugged this DPF had become. When the filter reaches this point, simply clearing the codes won’t fix the problem. The root cause needs to be diagnosed, and the DPF must be properly cleaned or replaced depending on its condition.
At QDC Auto Repair, we don’t just replace parts—we perform the proper diagnostics to determine why the DPF became restricted in the first place, helping prevent the issue from returning.
If your diesel truck isn’t performing like it should, let our team get it back to running the way it was designed.
📍 QDC Auto Repair
11812 N Tangerine Business Loop
Marana, AZ
📞 520-395-0435
Your diesel experts for diagnostics, repairs, and keeping your truck on the road. 🔧
DieselRepair

07/02/2026

❄️ A/C not blowing cold? The problem isn’t always the compressor.
This early 2000s Ford Mustang came in with an A/C system that wouldn’t engage. After diagnosing the system, we found the culprit—a failed CCRM (Constant Control Relay Module).
The CCRM houses several relays, including the A/C compressor relay. In this case, the relay inside the module had overheated and burned the circuit board, preventing power from reaching the A/C compressor.
Unfortunately, these relays are not serviceable separately. Since they’re built into the module, the only proper repair is to replace the entire CCRM assembly.
Problems like this are a great reminder that proper diagnostics matter. It’s easy to assume the compressor has failed, but replacing parts without testing can end up costing much more in the long run.
If your A/C isn’t blowing cold, let us find the real cause and get it fixed right the first time.
📍 QDC Auto Repair
11812 N Tangerine Business Loop
Marana, AZ
📞 520-395-0435
Quality diagnostics. Honest repairs. Done right the first time. 🔧❄️

06/25/2026

❄️ Think replacing an A/C evaporator is a simple job? Think again.
When an evaporator core fails, it’s buried deep inside the HVAC housing behind the dashboard. On this vehicle, the entire dashboard had to be removed just to access the evaporator.
These photos show:
🔧 The dashboard removed from the vehicle.
🔧 The HVAC housing removed from the cabin.
🔧 The old evaporator, which had become restricted and was no longer allowing the A/C system to perform properly.
This is one of the most labor-intensive A/C repairs on many modern vehicles, requiring hours of careful disassembly and reassembly to ensure everything goes back together exactly as it left the factory.
If your A/C isn’t blowing cold, has poor airflow, or you’ve been told your evaporator is leaking or restricted, we’re equipped to handle the job correctly the first time.
📍 QDC Auto Repair
11812 N Tangerine Business Loop
Marana, AZ 85658
📞 Call or Text: (520) 395-0435
Quality repairs. Honest service. Done right.

06/23/2026

🚨 Coolant Leak Found! 🚨
This radiator was leaking coolant and leaving the cooling system unable to properly maintain pressure. Over time, leaks like this can lead to overheating, poor engine performance, and potentially expensive engine damage if ignored.
The pink residue visible on the radiator is dried coolant from the leak path, making it easy to identify the source of the problem. We replaced the faulty radiator, pressure tested the system, and verified the cooling system was operating properly before returning the vehicle to the customer.
If you’ve noticed coolant spots under your vehicle, a low coolant warning, or your temperature gauge running higher than normal, don’t wait until you’re stranded on the side of the road.
📍 QDC Auto Repair
11812 N Tangerine Business Loop
Marana, AZ
📞 520-395-0435
Keeping your vehicle running cool and reliable, one repair at a time. 🔧🚗

06/18/2026

🌬️ Don’t forget about your cabin air filter!
This cabin air filter was completely clogged with dirt, dust, and debris. A dirty cabin filter can restrict airflow through your vents, make your A/C and heater work harder, create unpleasant odors, and reduce the air quality inside your vehicle.
If you’ve noticed weak airflow, musty smells, or it’s been a while since your last filter replacement, it may be time to have it checked.
A simple maintenance item like a cabin air filter can make a big difference in your driving comfort.
📍 QDC Auto Repair
11812 N Tangerine Business Loop
Marana, AZ
📞 520-395-0435
We’re here to help keep your vehicle—and the air you breathe inside it—in top shape! 🚗💨

06/10/2026

🔧 Not every radiator replacement is a quick job!
This 2023 GMC Sierra came into the shop with a coolant leak, and after a thorough inspection we confirmed the radiator had failed. What many people don’t realize is the amount of disassembly required to access and replace components on today’s trucks.
To replace the radiator on this Sierra, a large portion of the front end had to be removed to gain proper access and ensure the repair was completed correctly. It’s a great example of how modern vehicle repairs often involve much more than simply swapping out a part.
If you’ve noticed coolant spots on your driveway, a low coolant warning, or your vehicle running hotter than normal, don’t wait until it leaves you stranded.
📍 QDC Auto Repair
11812 N Tangerine Business Loop
Marana, AZ
📞 520-395-0435
Keeping Southern Arizona on the road, one repair at a time! 🚗💨