IllustrationDEFROSTER NOT WORKING WINDSHIELDD ICED OVER WHEN DRIVING FROM SNOW. WHEN STOPED DEFROSTER WILL OUTPUT ENOUGH HEAT TO MELT ICE. HEATER DEFROSTER IS SUB STANDARD INSUFFICIENT HOT WATER FLOW FROM REAR MOUNTED DIESEL ENGINE TO HEATER CORE ABOUT 37FT.
2004 Monaco Coach Diplomat
Owner reports · Recalls · Investigations
Limited comparison data
There is not enough comparable history to draw a useful model-year comparison.
About this comparison →How this year compares
Owner complaints by model year
Compare all Diplomat years →Counts vary with age, sales and reporting. They are not failure rates.
What owners reported most
All reported categories
Tap a category to read its complaints. One report may name several components.
When problems were reported
Mileage at the reported incident
Limited mileage data: 3 of 4 reports include usable mileage. There isn’t enough coverage to show a useful chart.
NHTSA’s mileage field refers to the reported incident, not necessarily the filing date. This shows report counts, not the likelihood of a failure.
What to inspect
Issues worth paying extra attention to based on owner reports.
- Electrical System. Review the 2 owner reports in this category and discuss these concerns during a pre-purchase inspection. Read reports →
- Service Brakes, Hydraulic. Review the 2 owner reports in this category and discuss these concerns during a pre-purchase inspection. Read reports →
- Structure. Review the 2 owner reports in this category and discuss these concerns during a pre-purchase inspection. Read reports →
NHTSA owner reports · September 18, 2026 snapshot.
0 crash reports0 fire reports0 injury reports
Visibility complaints
2 reportsDEFROSTER NOT WORKING WINDSHIELD ICED OVER WHEN DRIVING FROM SNOW AND FREEZING RAIN.WHEN STOPED DEFROSTER WILL OUTPUT ENOUGH HEAT TO MELT ICE. HEATER DEFROSTER IS SUB STANDARD.
Official recalls
104V441000 · Engine And Engine Cooling:engine:diesel
Sep 13, 2004
ON CERTAIN MOTORHOMES EQUIPPED WITH CUMMINS ENGINES, OIL CAN LEAK INTO THE ENGINE COMPARTMENT FROM A CRACK IN THE CUP PLUG.
Consequence & remedy
Consequence: OIL LEAKAGE ON A HOT ENGINE CAN RESULT IN AN ENGINE COMPARTMENT FIRE, POSSIBLY RESULTING IN INJURIES.
Remedy: CUMMINS IS CONDUCTING THE OWNER NOTIFICATION AND REMEDY FOR THIS CAMPAIGN. CUMMINS WILL INSTALL A STEEL CUP PLUG BOSS CAP TO ALL AFFECTED ENGINES. OWNERS SHOULD CONTACT CUMMINS CUSTOMER ASSISTANCE CENTER AT 1-800-343-7357 OR MONACO AT 1-800-685-6545.
Model-level recall history does not show whether a particular VIN is affected or has received a repair. Check a VIN with NHTSA ↗
NHTSA investigations
0No exact-year investigations in this snapshot.