Problems · NHTSA complaints

2003 Mitsubishi Diamante problems

Owners filed 69 complaints about the 2003 Mitsubishi Diamante with NHTSA between Jul 2003 and Jul 2019. The most-cited component is visibility (30).

Complaints
69
Filed with NHTSA
Crashes
3
Reported by owners
Fires
0
Reported by owners
Injuries
2
People reported injured
Deaths
0
Reported to NHTSA
01 —By component

Complaints by component

One complaint can cite several components
  1. Visibility30
  2. Engine and engine cooling18
  3. Power train8
  4. Service brakes, hydraulic5
  5. Tires4
  6. Equipment4
  7. Fuel system, gasoline3
  8. Structure3
  9. Suspension3
  10. Electrical system2
  11. Air bags2
  12. Latches/locks/linkages2
  13. Exterior lighting1
  14. Seats1

Complaints are unverified owner reports to NHTSA and are not normalized for sales volume. One complaint can cite several components.

Data from NHTSA Complaints API · synced Oct 28, 2026NHTSA vehicle page
02 —Trend

When complaints were filed

Does it get worse with age? Complaints per calendar year filed
View as table
Model yearComplaints filed per calendar year
20032
20049
200513
20069
200718
20088
20091
20105
20112
20120
20131
20140
20150
20160
20170
20180
20191

Mileage at failure isn’t a structured field in NHTSA complaint data, so we don’t chart it. Some owners mention it in their reports below.

03 —Owner reports

Top problems in owners’ words

Verbatim from NHTSA complaints, newest first

Visibility

30 reports
“INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6). THIS CONCERNS MY 2003 MITSUBISHI DIAMANTE. IT HAS LESS THAN 50,000 MILES ON IT AND IT HAS SUDDENLY STARTED SPEWING A LIGHT FILM ON THE INSIDE OF MY FRONT WINDSHIELD SO THAT I CANNOT SEE WELL...AND NOT AT ALL WHEN I AM HEADED INTO THE SUN. I HAVE CHECKED ON THE INTERNET AND A LOT OF PEOPLE ARE HAVING THE SAME PROBLEM WITH MITSUBISHI DIAMANTES GOING BACK SEVERAL MODEL YEARS. ALL DIAMANTES NEED TO BE RECALLED AND THE HEATER CORE AND/OR ITS O RINGS FIXED OR REPLACED. IF THIS DOESN'T HAPPEN, PEOPLE WILL DIE WHEN THEY SUDDENLY CANNOT SEE THE ROAD THROUGH THEIR FRONT WINDSHIELD. [XXX] *TR *DT”
Owner complaint to NHTSAFiled Mar 22, 2010VisibilityODI 10321417

Engine and engine cooling

18 reports
“I HAVE A 2003 MITSUBISHI DIAMANTE LS WITH 71677 MILES ON IT ALL OF THE SUDDEN MY HUSBAND (THE PRIMARY DRIVER) TELLS ME THAT EVERY TIME HE GETS OUT OF THE CAR HE FEELS LIGHT HEADED AND NAUSEOUS. DAYS LATER THE FRONT WINDSHIELD STARTED FOGGING UP WHILE DRIVING AND AFTER TURNING THE CAR OFF (WHETHER IT IS WARM OR COLD OUTSIDE) I GOOGLED WHY WOULD THIS HAPPEN AND HAVE SPOKEN WITH A FEW MECHANICS AND THEY ARE TELLING ME THAT IT IS THE HEATER CORE GOING OUT, AND THAT THE REASON WHY MY HUSBAND IS GETTING LIGHT HEADED AND NAUSEOUS IS BECAUSE THERE IS ANTI-FREEZE COMING INTO THE INTERIOR OF THE CAR WHICH IS VERY DETRIMENTAL TO YOUR HEALTH. I HAVE READ A TON OF COMPLAINTS ON DIFFERENT WEBSITES AND THEY ALL SAY THE SAME THING. I CONTACTED MITSUBISHI CORPORATE TODAY AND SPOKE WITH A [XXX] IN CUSTOMER SERVICE AND EXPLAINED TO HER WHAT WAS GOING ON AND ASKED WHY MITSUBISHI HAS NOT DONE ANYTHING ABOUT THIS. FIRST BECAUSE OF THE HEALTH IMPLICATIONS, SECONDLY BECAUSE OF THE SAFETY ISSUE OF THE WINDSHIELD FOGGING UP WHILE YOU'RE DRIVING TO WHERE YOU CAN'T SEE AND THIRDLY THAT FROM READING THE COMPLAINTS, THE HEATER CORE IS RIGHT ABOVE THE COMPUTER IN THE CAR SO IF THE HEATER…”
Owner complaint to NHTSAFiled Jun 2, 2011Engine and engine coolingODI 10404130

Power train

8 reports1 crash
“TL* THE CONTACT OWNS A 2003 MITSUBISHI DIAMANTE. THE CONTACT STATED THAT THE HEATER CORE FLUID LEAKED ONTO THE CENTRAL COMPUTER AND CAUSED THE TRANSMISSION TO FAIL. IN ADDITION, THE GEAR SHIFTER COULD NOT BE RELEASED FROM THIRD GEAR. THE VEHICLE WAS NOT TAKEN TO THE DEALER. THE VEHICLE WAS NOT REPAIRED. THE MANUFACTURER WAS MADE AWARE OF THE FAILURE. THE APPROXIMATE FAILURE AND CURRENT MILEAGE WAS 164,000. THE VIN WAS NOT AVAILABLE.”
Owner complaint to NHTSAFiled Mar 13, 2013Power trainODI 10502674

Service brakes, hydraulic

5 reports
“CAR SHAKES WHEN BRAKES ARE APPLIED. HAD BRAKES & ROTORS REPLACED AT 50,000 MILES. MECHANIC SAID ROTORS WERE TOO DAMAGED TO TURN. AFTER 6 MONTHS AND 20,000 MILES, THE CAR IS SHAKING AGAIN WHEN BRAKING. TOOK BACK TO MECHANIC, WHO CHECKED THE ROTORS AND SAID THEY NEED TO BE TURNED. I OWN A 1998 MITSUBISHI DIAMANTE, AND THAT CAR DOES NOT NEED THE ROTORS REPLACED EVERY TIME I REPLACE THE BRAKE PADS. MY DRIVING IS MOSTLY HIGHWAY, SO I DON'T USE THESE BRAKES MUCH. *JB”
Owner complaint to NHTSAFiled Apr 17, 2006Service brakes, hydraulic, EquipmentODI 10155554

Tires

4 reports
“TL* THE CONTACT OWNS A 2003 MITSUBISHI DIAMANTE EQUIPPED WITH COOPER CS3 TIRES (NA). WHILE DRIVING 25 MPH, AIR FROM THE VEHICLE'S FRONT DRIVER SIDE TIRE BEGAN TO BE RELEASED. THE CONTACT PULLED THE VEHICLE INTO A FUEL STATION/REPAIR SHOP WHERE THE TIRE WAS REPLACED. THE CONTACT TOOK THE VEHICLE TO THE INDEPENDENT MECHANIC THAT SOLD HIM THE TIRES. THE TIRES WERE MEASURED AND THE CONTACT WAS INFORMED THAT EACH OF THEM NEEDED TO BE REPLACED. THE DEALER WAS NOT CONTACTED. THE MANUFACTURER WAS NOTIFIED OF THE FAILURE. THE TIRE SIZE WAS UNKNOWN. THE APPROXIMATE TIRE FAILURE MILEAGE WAS 198,000 AND THE VEHICLE FAILURE MILEAGE WAS 216,242.”
Owner complaint to NHTSAFiled Jul 22, 2019TiresODI 11233933

Equipment

4 reports2 related recalls
“HEATER CORE (AND A/C CONDENSATE) LEAKS INTO PASSENGER COMPARTMENT CAUSING WINDOW TO "FOG UP". THIS COULD BE VERY DANGEROUS AS IT IMPAIRS THE DRIVERS SIGHT. *TR”
Owner complaint to NHTSAFiled Sep 26, 2007Visibility, EquipmentODI 10204227
Data from NHTSA Complaints API (owner reports, unverified) · synced Oct 28, 2026

Complaints are unverified owner reports to NHTSA and are not normalized for sales volume. One complaint can cite several components.