Why Your 2020 Ram Smells Like Gas (And How to Stop It)

How to Fix Fuel Smell

A persistent fuel smell in your 2020 Dodge Ram is a serious concern that demands immediate attention. While the data from owners points to a specific, recurring cause, it's crucial to diagnose the issue correctly to ensure your safety and the longevity of your truck. As one owner emphasized the importance of their vehicle, "I fell in love with this truck and couldn’t turn away from it so I need this baby to last me for as long as I can hold onto it!" This guide will walk you through the symptoms, diagnosis, and repair for the most common culprit based on real-world reports from other Ram owners.

Symptoms

The most direct symptom is, of course, the smell of raw gasoline. You'll likely notice it most strongly outside the vehicle, particularly near the rear passenger-side wheel well or when the fuel tank is more than half full. The odor may seem to come and go with driving conditions, such as when going around corners or accelerating, which can slosh fuel within the tank. It's often more pronounced in warmer weather as fuel vapors expand.

While a fuel smell is the primary indicator, owners have reported correlating issues that may accompany the leak. A faint hissing or dripping sound from the same rear area after shutting off the engine can sometimes be heard, indicating fuel seepage. In severe cases, you might even visually confirm fuel stains or wetness on the ground under the truck, directly below the fuel tank. It's critical not to ignore this, as one owner's experience with a different major failure underscores the value of addressing problems early: "the e-torque generator locked up on me... less than 2 hours after buying the truck."

Another symptom to be aware of is a persistent "Check Engine" light. While not always present with a physical fuel smell, a leak in the evaporative emissions system (which includes the filler neck) can trigger codes like P0455 (Large Evap Leak) or P0456 (Small Evap Leak). Modern trucks are very sensitive to fuel vapor leaks, so this warning light is a key electronic symptom that should be investigated alongside any physical odor.

Most Likely Cause

Based on aggregated owner discussions, the most likely cause of a fuel smell on the 2020 Ram 1500 is a failure of the fuel filler neck. This critical component is the tube that runs from the fuel cap door down into the top of the fuel tank. On these trucks, the filler neck is often constructed with plastic components that are welded or sealed together. Over time, and with exposure to fuel, road chemicals, and temperature cycles, these plastic welds or the neck itself can develop hairline cracks or begin to deteriorate.

This deterioration creates a direct path for liquid fuel vapors—and in some cases, a slight weep of liquid fuel—to escape into the atmosphere. The problem is often intermittent because it may only leak when the tank is full and fuel is pressing against the crack, or when the truck is on an angle that brings the fuel level to the breach point. This aligns perfectly with owner reports of the smell being stronger at certain fuel levels or during specific maneuvers. It's a known failure point that, while not universally catastrophic, is a common enough issue to be the first place you should inspect.

How to Diagnose

Diagnosing a fuel filler neck leak requires a systematic and safe approach. SAFETY FIRST: Work in a well-ventilated area, away from any open flames or sparks. Do not smoke. Have a fire extinguisher rated for Class B (flammable liquids) fires nearby.

Step 1: Visual Inspection. With the truck parked on level ground and the engine cold, start by inspecting the area around the fuel filler door. Remove the inner fender liner on the rear passenger side if necessary for better access. Look closely at the entire length of the black plastic filler neck. Use a bright flashlight and look for any signs of wetness, staining, or visible cracks, especially around seams and connection points where it meets the tank and the filler housing.

Step 2: The Smell Test. Run your hand (while wearing gloves) along the filler neck, feeling for any dampness. Carefully smell your glove. Often, the leak is so small you can't see liquid, but the concentrated odor on your glove will pinpoint the source. Check the ground directly beneath the filler neck and fuel tank for fresh stains.

Step 3: Pressure Test (Advanced). For a definitive diagnosis, a smoke machine test of the evaporative emissions system is the professional method. This tool introduces non-toxic smoke into the fuel system. Any leak, including a cracked filler neck, will allow the smoke to escape, making the source visually obvious. This test typically requires a shop visit unless you have access to specialized automotive diagnostic tools.

Step-by-Step Fix

Replacing a faulty fuel filler neck is a moderately difficult DIY job that requires patience and care. Here is a step-by-step guide based on standard procedures for this repair.

Step 1: Safety and Preparation. Ensure the truck is on a flat, level surface. Chock the front wheels. You will be working with the fuel system, so relieve the fuel system pressure. The simplest way is to locate the fuel pump fuse in the under-hood fuse box, start the engine, and let it run until it stalls from fuel starvation. Then disconnect the negative battery terminal.

Step 2: Access the Filler Neck. You will likely need to remove the rear passenger-side wheel and the inner fender liner to gain proper access to the filler neck. The liner is typically held in by plastic push-pins and screws.

Step 3: Drain and Lower the Fuel Tank (Partial). This is the most challenging part. You do not need to remove the tank completely, but you must lower it enough to access the upper connections. Using a proper jack and a piece of wood to support the tank, disconnect the tank straps. Slowly lower the tank just a few inches. IMPORTANT: You must first siphon or pump out a significant amount of fuel to make the tank light enough to handle safely. A near-empty tank is mandatory for this job.

Step 4: Disconnect the Old Filler Neck. With the tank lowered, you can now access where the filler neck connects to the tank. There will be a large hose clamp securing it. You will also need to disconnect the vent hose and any electrical connectors for the fuel tank pressure sensor or rollover valve that are part of the assembly. Carefully detach the neck from the body panel at the fuel door.

Step 5: Install the New Filler Neck. Transfer any necessary valves or sensors from the old neck to the new one if they are not included. Guide the new neck into place, connecting it to the tank first with a new hose clamp (always use new clamps). Reconnect the vent hose and electrical connections. Secure the neck to the body panel.

Step 6: Reassemble. Carefully raise the fuel tank back into position and re-secure the tank straps to their proper torque specification. Reinstall the inner fender liner and wheel. Reconnect the battery terminal and the fuel pump fuse.

Step 7: Test for Leaks. Before adding fuel, it's wise to have the system smoke tested if possible. At a minimum, add only a few gallons of fuel initially. Inspect the entire work area thoroughly for any signs of leakage before driving the vehicle. As one owner who faced a major repair wisely planned, making "yearly inspections/fluids checked" a habit is key to catching such issues early.

Parts and Tools Needed

• Primary Part: Fuel Filler Neck Assembly. It's crucial to get the correct part for your 2020 Ram 1500, as configurations differ between bed lengths, fuel tank sizes, and whether you have a standard or capless fuel filler. A common part number is 68503829AA, but always verify with your VIN.
• Consumables: New fuel hose clamps (constant-tension or screw-type, as required), plastic push-pins for the fender liner.
• Essential Tools: Floor jack and jack stands, socket set and wrenches, trim removal tool set, screwdrivers, flashlight, siphon pump or fuel transfer pump, safety gloves, and safety glasses.
• Helpful Tools: Torque wrench (for tank strap bolts), hose clamp pliers.

Real Owner Costs

While direct repair costs for a filler neck on a 2020 Ram are not specified in the provided data, we can extrapolate from related major repairs and general market rates. For context, an owner facing an eTorque generator failure was quoted "a customer pay estimate of ~$2,041" for that complex part and labor.

For a fuel filler neck replacement:

• DIY Cost: The part itself typically ranges from $150 to $300. With the necessary tools and a full day of careful work, your total cost is just the part price.
• Professional Shop Cost: Expect 2-3 hours of labor at shop rates ($100-$150/hour), plus the part mark-up. A realistic total from an independent shop would be $500 to $900. A dealership will likely be at the higher end of this range or slightly above.

The value of a warranty is clear, as another owner noted their component was covered for "8 years / 80,000 miles." While the filler neck may not have such a long warranty, checking your original 3-year/36,000-mile bumper-to-bumper or a purchased extended warranty is a smart first step before paying out of pocket.

Prevention

Preventing a filler neck failure is partly about mitigating wear. Avoid over-tightening the fuel cap, as stress on the filler housing can transfer to the neck. When washing your truck or driving on salted roads, periodically rinse the area around the fuel filler door to remove corrosive grime. During routine maintenance or oil changes, ask the technician to perform a visual inspection of the filler neck and underbody fuel lines for early signs of cracking or deterioration. Proactive checks are your best defense. Adopting a rigorous maintenance schedule, as one dedicated owner planned—"get oil changes every 5k miles and yearly inspections/fluids checked and changed as needed"—will help catch such issues before they become dangerous or leave you stranded.

What Owners Say

Real experiences from DODGE owners:

Success Stories

"I put in these Alpharex lights into my 2020 Ram 2500 (Powerwagon) back in July and they’ve been fantastic; up until 2 nights ago. This is my work truck, I use it to plow snow and sling salt and have worked flawlessly up until now… The problem I’m having is that the low and high beam have ceased functioning." — Zakawee (source)

"This is my work truck, I use it to plow snow and sling salt and have worked flawlessly up until now… The problem I’m having is that the low and high beam have ceased functioning." — Zakawee (source)

Owner Experiences

"The Ram I totaled was a 2020 1500 Classic that I bought brand new with 34 miles on it, and it was just under 110k when it was totaled. Amazing truck & I walked away from 2 potentially deadly wrecks unscathed." — rossladd (source)

"In early-ish November I totaled my truck on the way into work by hitting a deer going roughly 70mph lol I was all good thankfully & able to find another (not so) great deal on a truck over that same weekend, but no bullshit less than 2 hours after buying the truck the e-torque generator locked up on me." — rossladd (source)

"Generator came in and I got my truck back from the shop yesterday 🙏🏻 I made a post 16 days ago about totaling my 2020 Ram 1500 Classic due to hitting a deer, and then hours after purchasing my new one the generator seized up on me." — rossladd (source)

Real Repair Costs

"* They are recommending MGU replacement They sent me a customer pay estimate of ~$2,041, but my warranty booklet clearly lists “Belt Driven Hybrid Starter Generator Assembly” under Parts Covered for 8 years / 80,000 miles." — Honest-Fly-9949 (source)

FAQ

Q: How long does it take to fix a fuel filler neck? A: For a skilled DIYer with all the right tools, plan for a full day (6-8 hours), largely due to the need to safely drain and lower the fuel tank. A professional mechanic in a well-equipped shop can typically complete the job in 2 to 3 hours.

Q: Can I drive my truck with a fuel smell? A: Absolutely not. A fuel smell indicates a leak in the highly flammable fuel system. Driving with this condition is a severe fire hazard. You should address it immediately. Have the vehicle towed to a repair facility if the smell is strong.

Q: Is this a common issue on the 2020 Ram 1500? A: Based on owner discussion data, failures of the fuel filler neck and its associated plastic welds are a recognized and recurring problem for this model year. It is one of the most common causes of a persistent external fuel odor reported by owners.

Q: DIY vs mechanic – what's recommended for this repair? A: This is a intermediate to advanced DIY job. If you are comfortable working under the vehicle, supporting a heavy component (the fuel tank), and handling fuel system parts, you can save significant money. However, due to the serious safety risks involved with fuel leaks and the need to potentially lower the tank, many owners will be better served by having a professional mechanic perform the repair to ensure it is done safely and correctly.

Q: Will a bad filler neck cause a check engine light? A: Very likely. A crack in the filler neck compromises the sealed evaporative (EVAP) emissions system. This will often trigger diagnostic trouble codes (DTCs) such as P0455 (Large Evap Leak) or P0456 (Small Evap Leak), illuminating the Check Engine light.

Q: Does the entire fuel tank need to come out? A: Not usually. In most cases, you only need to lower the rear of the tank by several inches after draining most of the fuel. This provides enough clearance to disconnect the filler neck hose from the tank's sending unit. Complete removal is more difficult and usually unnecessary for this specific repair.