The Winnebago Navion is a Class C built on the Mercedes-Benz Sprinter diesel chassis, so the buyer concerns split into two stacks: the chassis (emissions/DEF system, expensive diesel service, NOx sensors) and the coach (the single large slide-out, the roof and seals, and house electrical). None of these are guaranteed defects on the unit in front of you. They are the areas where Navion owners most often report problems, so they are exactly where your inspection time and your dollars should go before you sign anything.
Below is a practical walkthrough for a nervous used buyer. Treat every dollar figure as an honest range to budget for, not a quote, and verify the specifics on the actual unit. When you have a listing in hand, you can get your RV verdict for a fast read on price and risk.
Start with the chassis: Sprinter diesel and the emissions system
The Navion's biggest "gotcha" is not really a Winnebago issue, it is the Mercedes Sprinter diesel and its modern emissions hardware. The same chassis powers a lot of the Class C motorhome market, so the concerns are well documented across owner forums.
What buyers most often report and what to research on the specific unit:
- DEF (diesel exhaust fluid) system faults. A failing DEF pump, heater, or sensor can throw warnings and, on some model years, trigger a limited-restart countdown that eventually keeps the engine from starting until repaired. Ask if any DEF or "Check Engine, restart limited" messages have appeared.
- NOx sensors and the SCR catalyst. These are common emissions-related repairs as Sprinters age.
- Emissions-related recalls and updates. Some Sprinter model years had emissions recalls and software updates. Check NHTSA recalls and complaints by the exact make, model, and year, and ask the seller for proof that open recalls were completed at a dealer.
Honest cost ranges to budget (verify on the unit, these vary widely by year and shop):
| Chassis item | Why it matters | Rough range to budget |
|---|---|---|
| DEF pump / heater / sensor repair | Can disable restart if ignored | $400 to $2,000+ |
| NOx sensor(s) | Common as mileage climbs | $400 to $1,200 each, installed |
| Diesel "A/B" service (oil, filters) | Required to keep warranty/history clean | $300 to $700+ |
| Glow plugs / hard-start diagnosis | Hard cold starts | $300 to $900 |
| Emissions / SCR catalyst work | Major, less common | $1,500 to $4,000+ |
Seller questions: "Do you have the full service history from a Mercedes or Sprinter-certified shop?" "Has the DEF system ever thrown a warning?" "Are all chassis recalls closed?" Walk-away trigger: a check-engine or DEF warning the seller "hasn't gotten around to," combined with no service records, on a diesel chassis.
The single slide-out: seals, motor, and floor
Most Navion floorplans use one large slide-out. A single slide is simpler than the multi-slide setups on a big Class A motorhome or fifth wheel, but it is still the most common moving point of failure on the coach.
Operate the slide fully in and out at least twice while you watch and listen:
- Listen for grinding, hesitation, or a motor that strains. Slide motor or gear repairs commonly run $300 to $1,500+ depending on the mechanism.
- Inspect the wiper and bulb seals all the way around. Cracked, flattened, or missing seal sections let water in.
- Push on the slide floor and look at the ceiling above the slide for stains. Water intrusion at the slide is one of the most expensive problems to chase.
For a deeper checklist on what good and bad slides look like, see our guide to RV slide-out problems. Walk-away trigger: a slide that will not fully retract or seal, plus soft spots in the slide floor.
Roof, seals, and water damage (the silent budget killer)
Water damage is the number one reason used motorhomes become money pits, and the Navion is no exception. The roof membrane, every roof penetration (vents, antenna, AC shroud, refrigerator vent), and the seams around windows and the entry door all rely on sealant that needs re-doing roughly every 1 to 3 years.
Get on a ladder (with the seller's permission) and inspect the roof yourself. Look for cracked or peeling sealant, ponding stains, and soft spots underfoot. Inside, check:
- Ceiling corners and the area around the overcab bunk for staining.
- Cabinet interiors along outside walls for swelling or a musty smell.
- The floor around the entry door and slide for spongy give.
Re-sealing the roof is cheap ($200 to $600 in materials and labor) but fixing the rot underneath is not. Soft, delaminated walls or a rotted floor can run $3,000 to $10,000+ and often is not worth fixing on an older coach. Study the warning signs in RV water damage signs and RV delamination before you view. Walk-away trigger: any soft floor or ceiling, a musty smell that does not clear, or fresh-looking sealant that suggests a recent patch over a problem.
House systems: power, heat, fridge, and the converter
The coach side of a Navion ages like any motorhome. Test every system, because "it works" on a listing is not the same as "I tested it."
- House batteries and converter/inverter. Ask the age of the house batteries (lead-acid typically lasts 3 to 5 years, $150 to $400+ to replace; lithium upgrades cost more). Confirm the unit charges on shore power and that 12V lights and pumps hold up.
- Absorption refrigerator. Many Navions use a propane/electric absorption fridge. These can fail or cool poorly with age. A replacement cooling unit or fridge runs $800 to $2,500+. Run it on both propane and electric for a few hours and confirm it actually gets cold.
- Furnace and water heater. Cycle both. Listen for the furnace igniting cleanly.
- Air conditioning. Run the roof AC and confirm it cools, not just blows.
- Generator (if equipped). Note hours and whether it has been exercised. A neglected generator that has sat for years often needs carburetor work, $200 to $600+.
Tires, weight, and the long-sitting unit
Motorhome tires almost always age out before they wear out. Check the DOT date code on every tire (including the spare). Tires older than 6 to 7 years should be replaced regardless of tread, and a set for a Sprinter-based Class C can run $1,200 to $2,000+ installed. Learn to read the codes in our RV tire age guide.
A unit that has been parked for a long time carries extra risk: dried seals, flat-spotted tires, stale fuel, a tired generator, and rodent damage to wiring. Ask how often it was driven and run. A Sprinter diesel that sits is often harder on the emissions system than one driven regularly.
Use the RV ownership cost calculator to fold these recurring costs (tires, diesel service, sealant) into your real annual budget, and the used RV offer calculator to translate any problems you find into a lower offer.
Your Navion inspection checklist
Bring this to the viewing. Confirm each item yourself rather than trusting the listing.
- Scan for dash and DEF warning lights at cold start and after warm-up
- Full service history from a Sprinter-qualified shop
- All chassis and coach recalls verified closed (check NHTSA by make/model/year)
- Slide operated fully in and out twice, seals intact, floor solid
- Roof walked and inspected, all sealant intact, no soft spots
- Ceiling, overcab bunk, and outside-wall cabinets checked for water stains
- Fridge cold on both propane and electric
- Furnace, water heater, and roof AC all cycled and working
- House battery age and converter/inverter charging confirmed
- Generator hours noted and unit started under load
- DOT date codes on all tires (replace if 6 to 7+ years)
- Title clean and lien-free (RV title and lien check)
For the full long-form version, see the used RV inspection checklist, and skim RV red flags before you drive out. More model breakdowns live in our guides and on the Winnebago brand page.
Frequently asked questions
Is the Winnebago Navion reliable?
The coach side is generally well regarded, and the Navion is popular for its compact size and diesel fuel economy. Most owner frustration traces back to the Mercedes Sprinter chassis: emissions-system faults and the cost of diesel service. A Navion with documented Sprinter service history and no open recalls is a very different buy than one with mystery maintenance.
What is the most expensive thing to go wrong on a Navion?
Two things compete: undetected water damage that has rotted the floor or walls (often $3,000 to $10,000+ and sometimes not worth repairing) and major emissions or diesel work on the Sprinter. Both are why a roof inspection and a cold-start warning-light check matter more than a clean interior.
How many miles is too many on a Sprinter-based Navion?
Sprinter diesels can run a long time with care, and well-maintained examples past 100,000 miles are common. Mileage matters less than service history. A 60,000-mile unit with no records and a DEF warning is riskier than a 120,000-mile unit with a binder of Sprinter-shop receipts. Always confirm the emissions system is healthy.
Do Navions have a lot of recalls?
Like most motorhomes on the Sprinter chassis, there have been chassis and emissions-related recalls over various model years. Do not rely on the seller's word. Check NHTSA recalls and complaints by the exact make, model, and year, and ask for dealer paperwork showing open recalls were completed.
Should I get a professional inspection before buying a used Navion?
Yes, and split it: a coach (RV) inspection for water, seals, and house systems, plus a Sprinter-qualified diesel shop for a chassis and emissions check. The combined cost (often a few hundred dollars) is small next to a single emissions repair or a rotted floor.
Found a Navion you like? Paste the listing and get your RV verdict before you call the seller.