NHTSA lists 2 safety recalls and 78 owner complaints for the 2001 Mitsubishi Diamante. Most complaints involve visibility (56) and engine and engine cooling (14). The EPA rates it 18 mpg combined.
CERTAIN PASSENGER VEHICLES FAIL TO CONFORM TO THE REQUIREMENTS OF FEDERAL MOTOR VEHICLE SAFETY STANDARD NO. 208, 'OCCUPANT CRASH PROTECTION.' THE BILINGUAL ENGLISH/SPANISH REMOVABLE AIR BAG WARNING LABELS AFFIXED TO THE DASH AND TO THE SUNVISOR DO NOT MEET THE SIZE REQUIREMENTS OF THE STANDARD.
CERTAIN SPORT UTILITY AND PASSENGER VEHICLES FAIL TO COMPLY WITH FEDERAL MOTOR VEHICLE SAFETY STANDARD NO. 225, "CHILD RESTRAINT ANCHORAGE SYSTEMS." THE OWNER'S MANUAL DOES NOT CONTAIN A STEP-BY-STEP DESCRIPTION FOR HEADREST ADJUSTMENT WHEN INSTALLING A CHILD RESTRAINT SYSTEM (CRS) TETHER STRAP.
Complaints are unverified owner reports to NHTSA and are not normalized for sales volume. One complaint can cite several components.
“WINDOWS ARE FOGGING UP DO T A FAULTY HEATER CORE. I REALLY DON'T MIND REPAIRING THE CAR SEEING THAT IT HAS 120K ON IT.. I PURCHASED THE CAR BRAND NEW AND THIS WILL BE THE 3RD HEATER CORE!!! WHAT'S GOING ON! *TR”
“MY CAR IS MAKING ME SICK!! I NOTICED A SMELL OF ANTI-FREEZE COMING OUT OF THE CLIMATE CONTROL VENTS. UPON FURTHER INVESTIGATION, I NOTICED ANTI-FREEZE/ENGINE COOLANT LEAKING FROM THE HEATER CORE DOWN ONTO FLOOR MATS, CLIMATE CONTROL INTAKE, ELECTRICAL WIRING INSIDE DASHBOARD, AND MORE IMPORTANTLY AUTOMATIC TRANSMISSION COMPUTER. THIS IS A SIGNIFICANT SAFETY AND HEALTH ISSUE AND NEEDS TO BE ADDRESSED IMMEDIATELY. WHERE IS MANUFACTURER'S RECALL. *JB”
“I HAVE A 2001 MITSUBISHI DIAMANTE, AND AM HAVING PROBLEMS THAT SEEM TO RUN RAMPANT AMONG THIS MODEL/MAKE. MY HEATER CORE WENT OUT AT ABOUT 100K MILES; MY ABS LIGHT STAYS ON (DUE TO A SPEED SENSOR FAIL), WHICH RENDERS THE WHOLE ANTI-LOCK SYSTEM USELESS; AND NOW MY ANTENNA MAST IS BROKEN. ALL OF THESE PROBLEMS ARE PRICEY TO FIX, AND MOST DIAMANTE USERS I HAVE FOUND EXPERIENCE AT LEAST A FEW OF THESE CONFLICTS. ANOTHER PROBLEM I HAVE SEEN MANY COMMENTS ABOUT IS TRANSMISSION FAILURE AT 113K MILES. MY CAR HAS EXACTLY THAT. ON TOP OF EVERYTHING, IT IS WINTER, AND ANTI-LOCK BRAKES ARE MUCH PREFERRED IN ICY WEATHER. I AM STARTING TO SMELL ANTIFREEZE AGAIN, THE WARNING SIGN TO A FAILING HEATER CORE, WHICH CAN LEAK ONTO A TRANSMISSION COMPUTER AND CAUSE IT TO FAIL AS WELL. I AM BEGINNING TO WORRY ABOUT BEING STRANDED, AND EVEN BEING SAFE IN MY CAR. I KNOW I AM NOT THE ONLY ONE COMPLAINING, BECAUSE I HAVE BEEN ONLINE ALL DAY READING FORUMS FROM PEOPLE WITH SIMILAR ISSUES (SEE THE FOLLOWING: HTTP://WWW.CARSURVEY.ORG/REVIEWS/MITSUBISHI/DIAMANTE/R76426/COMMENTS/PAGE-5/). SOMETHING MUST BE DONE! *TR”
Towing, payload and dimensions aren’t in the EPA or NHTSA data, so we don’t list them.
| Version | City | Hwy | Comb. | Fuel / yr | CO₂ g/mi |
|---|---|---|---|---|---|
| Diamante Auto 4-spd, 6 cyl, 3.5 L · Front-Wheel Drive | 16 | 23 | 18 | $4,200 | 494 |
| Item | Miles | Time | Note |
|---|---|---|---|
| Engine oil & filter | 5,000–10,000 mi | 6–12 months | Follow the oil-life monitor if fitted |
| Tire rotation | 5,000–7,500 mi | Every oil change | Check pressure monthly |
| Engine air filter | 15,000–30,000 mi | 1–2 years | Sooner in dusty areas |
| Cabin air filter | 15,000–25,000 mi | 1–2 years | |
| Brake fluid | — | 2–3 years | Absorbs moisture over time |
| Coolant | 60,000–100,000 mi | 5–10 years | Long-life coolants last longer |
| Spark plugs | 60,000–100,000 mi | — | Iridium/platinum plugs at the long end |
| 12V battery | — | 3–5 years | Heat shortens battery life |
2 safety recalls as of Nov 11, 2026, according to NHTSA. Recall repairs are free at a dealer. Check your VIN to see whether your car is included and whether the repair was done.
Owners filed 78 complaints with NHTSA. The most-cited components are visibility (56), engine and engine cooling (14), power train (4). Complaints are unverified owner reports and aren't adjusted for how many cars were sold.
The EPA rates the 2001 Mitsubishi Diamante at 18 mpg combined, depending on engine and drivetrain (1 version rated).