2000 Mitsubishi Diamante Problems

What owners report

Owners of this model year most often describe heater core leaks, with antifreeze smells in the cabin and windows that fog up and will not clear. Fogging is often worse with the heater running, and some owners say it appears suddenly, including at highway speeds. A smaller group of complaints describes stalling or power loss, often during right-hand turns.

1. 1
   Engine cooling

   Heater core leak with antifreeze smell in the cabin

   • 23 complaints (45%)
   • median 66,171 mi at 5.1 yrs old (16 state mileage)
   • 2 mention a crash, fire or injury
   • owner-quoted repair $1,100 (median of 7 quotes)
   • filed 2002–2008

   Owners describe a heater core leak that lets antifreeze into the cabin, usually noticed as a sweet or chemical smell through the vents and a wet passenger-side floor. Some complaints describe repeat heater core replacements, a faulty O-ring or gasket identified by the dealer, and dashboard removal for the repair. Some owners say the fumes made them feel unwell, and some say the problem is common for this model. Where mileage is given, reports range from about 32,000 to about 106,000 miles, and some describe the leak in relatively young cars.

   What to check: Ask whether the heater core and its gasket or O-ring have been replaced, and request records of any heater core bulletin work. Check the passenger-side carpet for dampness and smell the air from the vents with the heater running.

   2 excerpts from owner complaints in NHTSA records

   “My wife and I noticed antifreeze odor coming in through vents. When our windows would fog, our defroster wouldn't work. Then our passenger side floor was soaked with antifreeze. We took the car to the dealer, our heater core was leaking. Cost was $1300 to repair. Mitsubishi should be held responsible!! Too many complaints.”

   NHTSA complaint #10243955, filed 2008-09, 86,000 miles

   “Windows were not clearing properly and smell of anti-freeze was very strong. Upon calling the Mitsubishi dealer, I was told, it's probably the heater core. I ask if this is normal for a car less than three years olds with approximately 40,000 miles. The service manager told me, well to give you and idea, I just replaced one last week. I was told vehicle is out of warranty, cost to repair $650.”

   NHTSA complaint #10008109, filed 2003-02, 41,175 miles
2. 2
   Visibility (wipers, defrost, mirrors)

   Windshield fogs up and defroster cannot clear it

   • 23 complaints (45%)
   • median 60,342 mi at 5.2 yrs old (15 state mileage)
   • 3 mention a crash, fire or injury
   • owner-quoted repair $1,100 (median of 7 quotes)
   • filed 2000–2008

   Owners describe the inside of the windshield fogging up, sometimes suddenly and at highway speeds, while the defroster or defogger does not clear it. Some complaints say the fogging is worse with the heater on and leaves a whitish film on the glass, and some owners repeatedly wipe the glass with paper towels. Some describe reduced visibility that led to running off the road or a difficult drive home. Where mileage is given, reports range from about 34,000 to about 87,000 miles, and some describe fogging that appeared suddenly.

   What to check: During a test drive on a damp day, run the defroster and heater and check whether the windshield clears quickly. Ask whether any heater core or gasket repairs were done, since fogging complaints are often tied to that repair.

   2 excerpts from owner complaints in NHTSA records

   “About two months after buying a 2000 Diamante; in oct, 2004, I started to notice thick fog on the windsheild that wouldn't go away by using the de-fogger and when using the heater, I would also notice strong smell on anit-freeze comming out from the vent. Upon inspection, the dealership described the problem as faulty o-ring in the heater core. The fix was costly, around $1100.00 however the car has been problem free since then.”

   NHTSA complaint #10110292, filed 2005-02, 53,000 miles

   “Heater core on 2000 mitshubishi Diamante failed and fogged up my windsheild. While driving home the night of the failure, a deer jump in front of my car and caused 4 grand in damage. I had to pay for the heater core at the dealership.”

   NHTSA complaint #10112052, filed 2005-02, 82,000 miles
3. 3
   Engine cooling

   Stalling or loss of power, often in right turns

   • 6 complaints (12%)
   • median 60,342 mi at 5.5 yrs old (1 states mileage, few)
   • filed 2001–2005

   Owners describe the engine stalling or losing power, sometimes during hard right turns or when leaving a highway, and in some cases the power brakes and power steering also stopped working. Some complaints say the dealer agreed there was a problem but could not fix it. Other complaints describe stalling with black or blue smoke, a violent shake, and a warning light, and in some cases the vehicle would not restart. Mileage is mostly not recorded for these complaints, and some describe stalls during right turns or when exiting a highway.

   What to check: Ask whether any stalling repairs were made and request those records. A test drive that includes tight right-hand turns, along with a scan for stored fault codes, may help check for this symptom.

   2 excerpts from owner complaints in NHTSA records

   “Ill be brief  I own the above car and have a safety problem that is not being fixed by Mitsubishi. With about < tank of gas in the car, a hard right turn or exit off the expressways, causes the car to completely stall  no power steering, brakes, no acceleration. Worse, this is a problem with all diamantes (verbal via the service rep for the chicago area  jeff hampton). I have been in a situation more than once where this has almost produced a rear end accident by semi trucks and other vehicles. …”

   NHTSA complaint #755964, filed 2001-12

   “While making a right turn (in partivularly off a major highway) the car wilstall - no power, brakes, or power steering. Numerous complaints have beent odealer and they have mmentionedthta this is a problem with thevehicle but cannot be fixed. Please note that with the car stalling at such speeds, getting rear ended is inevitable in particular with trucks.”

   NHTSA complaint #757068, filed 2002-01

Buying note. When considering this model year, ask for records showing whether the heater core, its gasket or O-ring, and the cooling system were serviced, and whether any stalling repairs were made. During a test drive, check the windshield defogging and the cabin for an antifreeze smell.

Summary written with AI from a sample of 47 NHTSA complaints for this model year (picked at random, with complaints that state a mileage and recent ones taken first), then checked automatically against the source records. Where a problem shows a complaint count, every complaint for this model year was matched with fixed keyword rules (written with AI and tested against the sample), and the mileage, age and repair figures are calculated from those complaints; owners' figures are as stated, not verified. Other counts refer to the sample. The excerpts come from NHTSA's public complaint records and are unverified; capitalisation is normalised, NHTSA staff notes are removed, and shortened text ends with “…”. Something wrong? Request a correction.