NHTSA — Visibility: Defroster/Defogger System: Windshield: Heater Core Problems

2001 Mitsubishi Diamante (Page 2 of 3)


really awful
Crashes / Fires:
0 / 0
Injuries / Deaths:
3 / 0
Average Mileage:
45,035 miles

About These NHTSA Complaints:

This data is from the NHTSA — the US gov't agency tasked with vehicle safety. Complaints are spread across multiple & redundant categories, & are not organized by problem.

So how do you find out what problems are occurring? For this NHTSA complaint data, the only way is to read through the comments below. Any duplicates or errors? It's not us.

2001 Mitsubishi Diamante accessories - exterior problems

accessories - exterior problem

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2001 Mitsubishi Diamante Owner Comments (Page 2 of 3)

« Read the previous 20 complaints

problem #32

Jan 252006

Diamante 4-cyl

  • Automatic transmission
  • miles


We noticed black residue on the rear windshield of 2001 Diamante. The next day when the defroster was turned on black smoke filled the inside of the car. The following day black smoke filled the car without the defroster being on. Had the car towed, and they told us it was the heater core having a hole in it. They had another 2001 Diamante sitting there with the exact same problem. Since it wasn't under warranty, we bought it certified in December, it will cost approximately $875 to fix it.

- Indianapolis, IN, USA

problem #31

Oct 252005

Diamante 6-cyl

  • Automatic transmission
  • 47,971 miles
Abnormal smell coming from vents, made me, and my two sons feel nauseous, created a headache for me. I had to open windows in order to drive car due to fumes. Brought car to dealer, and heater core was identified as problem and needed to be replaced. Dealer said this is a very common problem with this year and model. I asked if there was a manufacturer recall and he said no, they only had to do a recall if it was a safety problem. This cost $802.37 to repair. This is most definitely a safety issue. Not only health, but can cause an accident due to fogging of windows, etc. I am sure Mitsubishi knows of this problem. Seems as though a class action suit should be filed against them for this issue. My car only has 47K miles, I purchased new and it has had all regular maintenance required. This is obviously a manufacturers defect. I will never purchase another Mitsubishi, just because they do not take responsibility.

- Lake Forest, CA, USA

problem #30

Oct 212003

Diamante 6-cyl

  • Automatic transmission
  • 30,162 miles
Noticed smell of antifreeze in the passenger compartment. Front windshield fogs up after car is driven and the motor is turned off. Wiping off the moisture is the only way to remove it. Read about the heater core problems on the web and took the car in to be repaired for this specific problem. Core seals were replaced Oct 2003, the first repair, but smell of coolant remained. Two additional attempts at repair were made, including "cleaning" of the core, but smell remains to this day.

- Atlanta, GA, USA

problem #29

Oct 132005

Diamante 6-cyl

  • Automatic transmission
  • 72,000 miles


Vehicle is 2001 Diamante ls with 72,000 VIN # [xxx]. defroster not working properly window fog smell of antifreeze and puddle of antifreeze under passenger rug. Have estimate of $800 to fix. Updated 07/18/2012 information redacted pursuant to the Freedom Of Information Act (FOIA), 5 U.S.C. 552(B)(6)

- Salem, NH, USA

problem #28

Feb 282004

Diamante 6-cyl

  • Automatic transmission
  • 42,853 miles
I have a 2001 Mitsubishi Diamante ls that requires I replace the heater core, this has been a problem since I purchased this vehicle. I also owned a 1998 Diamante ls with the same problem.

- Roslindale, MA, USA

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problem #27

Jul 152005


  • Automatic transmission
  • 72,000 miles
Car smelled of syrup when the heat was on and smoke came from the vents. After breaking down, I was told by the dealership that the O rings/heater core needed to be replaced which cost me $850..

- Washington, DC, USA

problem #26

Mar 112005

Diamante 6-cyl

  • Automatic transmission
  • 52,000 miles


Coolant from failed O-rings in heater core caused windows to fog over while driving.

- Maple Grove, MN, USA

problem #25

Jan 052005

Diamante 6-cyl

  • Automatic transmission
  • 28,000 miles
In early 2005, I started noticing that my windows were fogging for no reason while driving and it was hard to defrost them. A definite safety hazard, because I could not see that well. Later, I started noticing a weird smell in the cabin. (it turned out to be coolant; it can't be good for your health) in mid 2005, I saw fog/smoke coming from the vents. A repair shop confirmed that it was a problem with the heater core, and it would be at least $800 to fix. The dealer told me that my car is out of warranty. I purchased the vehicle in December 2001, and it now has only 30600 miles.

- Milpitas, CA, USA

problem #24

Jul 252005

Diamante 6-cyl

  • Automatic transmission
  • 36,000 miles
Low mileage 2001 Mitsubishi Diamante has a failed heater core. Results in excess ethelyne glycol vapor in the passenger compartment and fogged windows. Search of the web shows problem to be common.

- San Francisco, CA, USA

problem #23

May 022005


  • miles
2001 Mitsubishi Diamante experienced problems with the heater core. The heater core had to be replaced because anti-freeze was leaking into the passenger compartment and fogging the windshield. When the heater core was being removed, the consumer noticed it failed to have sufficient insulation. The oil pan gasket was leaking and the upstream oxygen sensor was replaced.

- Seaside, CA, USA

problem #22

May 182005

Diamante 6-cyl

  • Automatic transmission
  • 26,000 miles


Consumer owns a Mitsubishi 2001 vehicle with less than 26,000 miles the heater core is not working. We noticed some type of a fog in the window. We started getting smoke in the car, and the front glass fogs up and doesn't clear up. Also, it has a strong smell of antifreeze. We have to keep putting antifreeze in the car.

- Mount Vernon, NY, USA

problem #21

Apr 022005


  • 49,000 miles
Complaint received via E-mail. The heater core had to be replaced because of leaking antifreeze into the passenger compartment and fogging of windshield. When I took my vehicle in I was advised at that time there was another Diamante (2002) that required a heater core, and the vehicle at approximately 42,000 miles. When the heater core was being removed I noticed it failed to have sufficient insulation as this could cause failure by vibration over normal roads.

- Seaside, CA, USA

problem #20

Mar 202005

Diamante 6-cyl

  • Automatic transmission
  • 40,000 miles
This is a Mitsubishi Diamante 2001 ls. I'm experiencing pungent smell of anti-freeze inside the car as soon as I turn on heating. The dealer I got the preowned car from won't fix the problem unless I can show them the leak in heater core. Anti-freeze contains ethylene glycon and the fumes are highly toxic. Fixing the the heater core will cost $1000. I am filing this complaint to ascertain that this is a very very common problem in Mitsubishi Diamante and Mitsubishi motors should be aware of three main risk associated with this: (1) the defect exposes customers to unusual level of toxic ethylene glycol which should not exceed 10-25 ppm levels (consult msds for ethylene glycol) (2) the leak can affect the car's microprocessor and poses a severe hazard for drivers. (3) faulty heater core makes the visibility difficult due to fogging of wind shield thus putting the driver at greater risk. I will eventually fix the problem by spending $1000 after the summer if Mitsubishi refuses to issue a recall. Right now I am trying some radiator anti-leak to delay the costly repair. But I want NHTSA to be aware of the hazards that has been ignored by the manufacturer.

- Powell, WY, USA

problem #19

Dec 202004

Diamante 6-cyl

  • Automatic transmission
  • miles
The driver noticed that the passenger side defroster was inoperative. Antifreeze was leaking from the passenger side door. The passenger side window fogged and caused poor visibility to the driver. The driver contacted the dealer and was informed that the heater coil needed to be replaced. Antifreeze smells the car up and leaks onto the floor carpet damp. Dangerous to drive because of fog up.

- Chilhowie, VA, USA

problem #18

Feb 152005

Diamante 6-cyl

  • Automatic transmission
  • 75,000 miles
Heater coil replacement. Causes car to overheat, also causes bad smell and heat and fumes to come out of the dash. It has come to my attention that a large amount of Mitsubishi Diamantes up to year 2001 have this problem and it has not be considered a recall. I wanted to know why and how this issue can be fixed. It's not fair that customers have to pay over 1000. To get something fixed that is obviously a manufacturer problem. This is not an optional fix since it can ultimately cause an engine fire.

- Fredericksburg, VA, USA

problem #17

Feb 112005

Diamante 6-cyl

  • Automatic transmission
  • 78,000 miles
Heater core failed. This caused my windshield to fog up. My car smells like antifreeze so bad that I got a migraine. The repair is approximately $600.

- Waukesha, WI, USA

problem #16

Apr 012004

Diamante 6-cyl

  • Automatic transmission
  • 45,000 miles
Coolant leaking into rug on front passenger side, coolant fumes leaking from air vents, constantly adding more coolant to car, foggy windows that would not clear up even after an hour of driving, scent in car that kind of smells like syrup. Constant headaches, nausea when driving inside vehicle, hard to drive due to foggy windows. Took car to dealer and had heater core replaced. Faint scent of syrup still remains in car.

- North Bergen, NJ, USA

problem #15

Feb 052005

Diamante 6-cyl

  • Automatic transmission
  • 41,000 miles
I have had my 2001 Mitsubishi Diamante for one year now and have always found that my front window fogged over with a film the defroster would not remove. Last weekend the 5th of February 2005 I noticed the film getting worse and the car filled with a very pungent smell of antifreeze this caused my eyes to burn and made it hard to continue driving. I took it to my dealer who said the heater core had a leak and I needed new gaskets that were $16 dollars a package and that labor would be $492 dollars for 5 hours. I was quite shocked it would cost so much considering I have well maintained my car and that I only had 41,000 miles on it. I am concerned of the health effects if I have been breathing in antifreeze for over a year now. I am also concerned that the leakage may have caused damage to my ECU because of where the leak is (right above the ECU). I have read that this may be a common problem with the Diamante and my dealer said he has seen a few himself (he knew exactly what it was when I told him what was happening and how much it cost). I fear Mitsubishi is aware of this problem and the long term affects it may have on health and safety and hasn't come forward to fix the problem.

- Lonmont, CO, USA

problem #14

Jan 212005

Diamante 8-cyl

  • Automatic transmission
  • miles
The heater core developed a leak which resulted in the window fogging up, followed by smoke/steam from the anti freeze coming through the air vents. This reduced the driver's visibility while driving, and could cause an accident.

- Waldorf, MD, USA

problem #13

Jan 312005

Diamante 6-cyl

  • Automatic transmission
  • 60,000 miles
Heater core, producing toxin fumes, inside the car. This is my only means of transportation, I have a two year old child who I drive around every day.this is going to cost me $400 dollars in labor, which I do not have, I have no idea what the heater core cost. But it must be fix before my family or I come down with some serious illness.

- Bronx, NY, USA

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