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Mitsubishi DiamanteModel year report

2002 Mitsubishi Diamante Problems

Complaints
123filed with NHTSA
Median mileage
60,000miles, 91 complaints with mileage
Recalls
3campaigns on record
Trend
StableComplaints filed in the last 3 full calendar years are within 25% of the 3 years before.
NHTSA crash rating
—overall rating starts with 2011 models
EPA fuel economy
18 mpgcombined, 3.5L 6-cyl FWD · 16 city / 23 hwy

Sources: NHTSA records for the 2002 Mitsubishi Diamante (complaints, recalls, investigations), EPA fuel economy. Report an error

What owners report

Owners of the 2002 Diamante most often describe coolant leaking inside the cabin from the heater core, which fogs the windshield and leaves a sweet smell in the passenger compartment. A smaller group reports overheating and coolant loss, along with occasional transmission and electrical problems. Most reports in the sample arrive between roughly 35,000 and 90,000 miles.

  1. Visibility (wipers, defrost, mirrors)

    Heater core leak fogging windows, coolant smell inside

    Mentioned in 42 of 60 sampled complaints

    Owners describe a sweet, syrup-like coolant odor from the vents, a greasy film on the inside of the windshield, and windows that fog up and resist defrosting. Many also find the passenger-side carpet damp with coolant. According to complaints, dealers typically diagnosed a leaking heater core or its O-rings and quoted repairs in the range of several hundred to over a thousand dollars; some owners report the leak returning after seals were replaced. Reported mostly from about 35,000 to 90,000 miles, often first noticed when the heater is used in cooler weather.

    1 related service bulletin

    What to check: Ask whether the heater core or its O-rings have been replaced and whether the carpet has been wet; check the passenger floor for dampness and smell the vents with the heater on.

    2 excerpts from owner complaints in NHTSA records

    “The heater core. I start smelling an antifreeze smell inside the car then the check engine soon light came on. Also the tcl is on. The dealer said that it is a wheel sensor that will run me $625. The heater core is $1,200. Every one that I talk to on the email sight is having the same problem. Please help! Thanks.”

    NHTSA complaint #10230393, filed 2008-06, 63,000 miles

    “My front windshield was fogging up every time I used the heater and a smell of coolant inside my car--nasty film was left, found out it was a heater core problem. Sometimes the fog would take 20 minutes to clear up with defroster on highest settings. These problems are all over the internet with Mitsubishi diamantes. I am surprised that these have never been recalled for safety reasons.”

    NHTSA complaint #10296309, filed 2009-12, 60,000 miles
  2. Electrical system

    Coolant reaching computer, check engine light and stalling

    Mentioned in 8 of 60 sampled complaints

    Owners report that coolant from the heater core drips onto the control module mounted below it, after which the check engine, TCL or ABS lights come on, the engine cuts out or runs erratically, and the transmission shifts poorly. Complaints describe dealers replacing computers or transmission relays without stopping the leak, and some say the leak itself was the underlying cause. Reported from roughly 20,000 to 90,000 miles, usually after a heater core leak has gone on for a while.

    Recall 02V1000012 related service bulletins

    What to check: Look for coolant staining or dampness around the module under the passenger dash and note whether warning lights come on; ask whether the heater core leak was fixed before any electronics were replaced.

    2 excerpts from owner complaints in NHTSA records

    “I have a '02 Mitsubishi Diamante and I have had problems out of the heater core leaking and now its affected my ecu (computer) I call the dealership and they want outrageous prices to fix or even check my car.. I think that since its a problem from the dealer they should recall these cars.. I know I will never buy another Mitsubishi and I will never recommend them to a friend.. What can be done about this problem?”

    NHTSA complaint #10290728, filed 2009-11, 94,000 miles

    “At approx 60k (I am the original owner) the car began to emit mist from the vents. The first incident was a near overheating event which caused me to check the coolant. After topping off the level the car operated normally for a few months and then repeated the behavior. The tcl went off, the check engine light came on, the mist got heavier, and the car is a danger to both myself as an operator and others on the highway because the fog from the antifreeze damages visibility. …”

    NHTSA complaint #10250921, filed 2008-12, 60,000 miles
  3. Engine cooling

    Coolant loss and overheating

    Mentioned in 4 of 60 sampled complaints

    Complaints describe the coolant level dropping without an obvious external leak, the temperature gauge climbing in traffic, and a mist coming from the dash vents. Several owners connect this to the same heater core leak, since coolant leaves the system inside the cabin rather than under the car. Typically reported between about 50,000 and 80,000 miles.

    What to check: Check the coolant reservoir level and look for dye or crusty residue at the heater hoses and under the passenger dash; ask whether cooling-system pressure has been tested.

    2 excerpts from owner complaints in NHTSA records

    “My wife and I own a 2002 Mitsubishi Diamante vr-x. This past june 2005 I started noticing the car was overheating when I would stop at lights or in traffic. At first I figured it was the really hot weather we were having. After a day or so I noticed the engine temperature would fluctuate even at higher speeds, so I pulled into a gas station and checked the coolant. It was low. I bought some coolant and filled up the reservoir thinking I had found my problem. …”

    NHTSA complaint #10132569, filed 2005-08, 50,000 miles

    “At about 70,000 miles I started to see a very fine mist-like smoke coming from the dash while driving. There were no warning lamps illuminated on the dash. So after the temp gauge started to go up and I could also smell anti-freeze. I checked the radiator area and could find no leak but when I checked the coolant it was low. I topped off the coolant and a couple of months later it did the same thing. I then added stop-leak and the coolant level seems to be staying but I can still smell the anti-freeze and the windows fog up. …”

    NHTSA complaint #10246942, filed 2008-10, 70,000 miles
  4. Transmission and drivetrain

    Transmission failure or harsh shifting

    Mentioned in 4 of 60 sampled complaints

    Some owners describe the transmission slipping, flaring between gears or quitting entirely, in one case leaving the car stopped in an intersection. Others report harsh shifts that appeared alongside the coolant leak onto the electronics. Complaints mention transmission replacement and repair advice from shops. Generally reported from about 60,000 miles upward, including one case past 140,000 miles.

    1 related service bulletin

    What to check: Test drive through all gears from cold and warm, check for delayed or flared shifts, and ask for transmission service records.

    2 excerpts from owner complaints in NHTSA records

    “I was driving my Mitsubishi across the university bridge on 7-28-2017 and suddenly the transmission went out and I was stuck and had no power of movement,my wife and 3 y.o.child were passengers in the car,luckily the state patrol came and assisted us.the dealer told us that this car was mechanically sound and had no problems or issues.they lied to us and by doing so they put our lives in danger.the drivers side air bag was also missing when we purchased the car.”

    NHTSA complaint #11012456, filed 2017-08, 143,000 miles

    “I own a 2002 Mitsubishi Diamante car, I bought this car in 02 since the 1st day I bought the car there was problems. The computer in the car went crazy my check engine light,,cruise control,anti lock brake, tcl light all started flashing . I took the car back to the dealer & they replaced the computer but it didn't work they put 3 computers in since then, these lights are still on till this day. In 06 my trans blew I took the car back to the dealer they replaced my trans the car still doesn't ride right. …”

    NHTSA complaint #10236534, filed 2008-07, 20 miles
  5. Tires

    Rear tire wear from worn rear knuckle bushings

    Mentioned in 4 of 60 sampled complaints

    Owners report the rear wheels tilting inward, inside edges of the rear tires wearing out quickly, and the car feeling unstable in rain or snow. Complaints describe alignment shops being unable to bring the rear within specification and dealers replacing the rear knuckle bushings. Reported from about 60,000 to 95,000 miles.

    What to check: Inspect the rear tires for uneven inner-edge wear and ask for a recent four-wheel alignment printout.

    2 excerpts from owner complaints in NHTSA records

    “Goodyear eagle tires, make winding noise when vehicle is in motion. Dealer claimed that this was caused by lack of tire rotation, I have rotated this tires every 6,000 miles, since the day I bought the car new. The problem started after the car had about 2,000 miles, car has been to the dealer two times and the problem has not resolved, vehicle has 24,000 miles, it came with 36,000 miles bumper to bumper warranty. …”

    NHTSA complaint #10041278, filed 2003-10, 2,000 miles

    “At about 95000 miles I noticed the vehicle becoming very hard to drive whenever there was slight moisture or snow on the roads. After inspecting I noticed both rear wheels tipped in at the top substantially. The left rear wheel was also towed out at the front and both rear tires were almost completely worn even though I had just replaced them about 25000 mile prior. I took it to a local shop who informed me that there was a technical service bulletin out for bushings that press into the rear knuckles wearing prematurely. …”

    NHTSA complaint #10246947, filed 2008-10, 90,000 miles

Buying note. Have a used Diamante of this year inspected for a leaking heater core, including the carpet and the control module area under the passenger dash, and confirm any coolant-related repairs were done. A test drive covering transmission shifts and a look at rear tire wear will cover the other commonly reported items.

Summary written with AI from a sample of 60 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. Counts refer to that 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.

NHTSA recorded 123 consumer complaints for the 2002 Mitsubishi Diamante. 91 of the complaints include a mileage, and 30% of those were filed for vehicles with under 50,000 miles; the median is 60,000 miles. Of all complaints, 4 involved a crash, 11 an injury, 2 a death, according to the filers. NHTSA lists 3 recall campaigns and 25 technical service bulletins for this model year.

Not compared (before 2008). Model years 2008–2023 of the same vehicle that have at least 25 complaints are compared, and a model needs at least 3 of them.

Which parts are reported most

Complaints can name more than one part, so the counts add up to more than the total. Select a part to see its complaints, recalls and bulletins.

Also reported: Other or unknown (2), Suspension (2), Wheels (2), Electronic stability control (1), Engine (1), Latches, locks and linkages (1), Steering (1), Vehicle speed control (1).

Example complaints

Visibility (wipers, defrost, mirrors): “Car cabin has strong odor of antifreeze when using the heater. Windows have difficulty de-fogging and after contacting service department, was told that it would be over $1000 to fix. As I dug deeper into my problem, I found that I am not the only owner of my vehicle that has had this problem, and my repair forum had this link to file a report.”

NHTSA complaint #10196441, filed 2007-07, 113,800 miles

Engine cooling: “My 2002 Mitsubishi Diamante has o ring failure in the heater coil. I have read many complaints that this is common on this model and would like a recall on these vehicles due to the extreme nature of the issue. With the failure of the o rings come potential anti freeze vapors entering passenger compartment and causing physical damage to all passengers. It may also cause the car to overheat in the middle of heavy stop and go traffic and cause accidents and/or death. …”

NHTSA complaint #10279201, filed 2009-08, 78,000 miles

Transmission and drivetrain: “January 12, 2005 one cold morning I noticed that the reverse gear did not go in as fast as it should it took like 1 minute to go into gear, when cold it would jolt before advancing in drive. Took it to the dealer, they did not find anything, so I picked up that same afternoon, next morning same problem. …”

NHTSA complaint #10110114, filed 2005-02, 52,700 miles

Electrical system: “While driving at any speed electrical system failed. As a result, the vehicle stalled in oncoming traffic. It was later determined by the dealer's technician that the etacs systems failed.”

NHTSA complaint #10072280, filed 2004-07, 21,076 miles

Mileage when problems were reported

30% of the 91 complaints with a mileage were filed for vehicles with under 50,000 miles; the middle half falls between 44,000 and 78,000 miles.

5%0–103%10–2521%25–5041%50–7522%75–1008%100–1500%150+
Share of complaints by mileage when the problem was reported, in thousands of miles (91 complaints with mileage). Red bars: under 50,000 miles. Bucket widths differ. Median: 60,000 miles.

Complaints by year filed

Trend: stable. Complaints filed in the last 3 full calendar years are within 25% of the 3 years before.

’02’04’0626’08’10’13’17
Complaints by year the complaint was filed with NHTSA. Red bars: the last 3 full calendar years used for the trend. The current year (2026) is partial.

Fuel economy and running cost

EPA ratings for each 2002 Mitsubishi Diamante version. Annual fuel cost is the EPA's estimate at its current fuel prices for 15,000 miles a year (55% city driving).

VersionEngineTransmissionCityHwyComb.Fuel / yr
Diamante FWD3.5L 6-cyl4-speed automatic162318$4,550

Source: U.S. EPA and Department of Energy, fueleconomy.gov. Ratings are for comparing vehicles; real-world mileage varies with driving and conditions.

Recalls and investigations

Recall details for the 2002 Mitsubishi Diamante → · Check a VIN at nhtsa.gov/recalls

Technical service bulletins

TSBs are manufacturer notes to dealers about known repair procedures. They are not recalls and do not by themselves mean a vehicle has a fault. 25 on record; the latest 10 are shown.

See all 25 bulletins →

Other model years of the Mitsubishi Diamante

YearComplaintsMedian miRecallsCrash ★MPGScore (50 = typical)Trend
20035657,5002—18Not compared (before 2008)Stable
200212360,0003—18Not compared (before 2008)Stable
20017859,7502—18Not compared (before 2008)Stable
20005157,1713—18Not compared (before 2008)Stable
19992386,4502—18—Stable
19982771,7501—18Not compared (before 2008)Stable
199734111,5660—19Not compared (before 2008)Stable
199512137,5000—19—Not enough data
19942750,0152—19Not compared (before 2008)Stable
1993291083—18Not compared (before 2008)Stable
199242120,0002—19Not compared (before 2008)Stable

All Mitsubishi Diamante model years · Best and worst years by complaints

Frequently asked questions

What are the most common problems with the 2002 Mitsubishi Diamante?

Owners of the 2002 Diamante most often describe coolant leaking inside the cabin from the heater core, which fogs the windshield and leaves a sweet smell in the passenger compartment. The issues reported most often: Heater core leak fogging windows, coolant smell inside; Coolant reaching computer, check engine light and stalling; Coolant loss and overheating.

How many NHTSA complaints does the 2002 Mitsubishi Diamante have?

NHTSA recorded 123 consumer complaints for the 2002 Mitsubishi Diamante as of Oct 30, 2026. Complaints are unverified consumer reports and may be duplicated or inaccurate.

What part of the 2002 Mitsubishi Diamante is reported most often?

Visibility is named most often, in 71 complaints (58% of the total), followed by engine cooling with 38.

Has the 2002 Mitsubishi Diamante been recalled?

NHTSA lists 3 recall campaigns for this model year. To check a specific vehicle, enter its VIN at nhtsa.gov/recalls.

What gas mileage does the 2002 Mitsubishi Diamante get?

The EPA rates the 2002 Mitsubishi Diamante (Diamante, 3.5L 6-cyl) at 18 mpg combined, 16 city and 23 highway, with an estimated annual fuel cost of $4,550 at 15,000 miles a year. Other engine and drive versions are rated differently.

At what mileage are problems with the 2002 Mitsubishi Diamante reported?

Among the 91 complaints that include a mileage, the median is 60,000 miles and the middle half falls between 44,000 and 78,000 miles; 30% were filed for vehicles with under 50,000 miles.

About this data. Data from NHTSA (ODI) complaints, recalls, TSBs and investigations, updated Oct 30, 2026. Complaints are unverified consumer reports and may be duplicated or inaccurate. Fuel economy is from the EPA and DOE (fueleconomy.gov).

Complaint counts come from NHTSA’s public complaint database; we count each complaint once. The source records for this vehicle are on nhtsa.gov. Scores and trends are our own summaries of that data, described in the methodology. This page is not legal, safety or repair advice: for a specific vehicle, check its VIN at nhtsa.gov/recalls and ask a qualified mechanic. See an error? Tell us.