Huge win for car owners! All TSBs to be made public. The Center for Auto Safety just made the NHTSA (US Government) make public the full text of all TSBs from now on. They are the same organization that has petitioned the NHTSA & filed lawsuits to protect car owners over exploding gas tanks & other major safety issues. Whenever you drive in your car, you are safer thanks in part to a lot of work over the years by this small but very effective consumer advocacy group.

Please take a moment & say thank you by donating $5 or whatever you can to the Center for Auto Safety.


really awful
Crashes / Fires:
0 / 0
Injuries / Deaths:
1 / 0
Average Mileage:
51,984 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.

2002 Mitsubishi Diamante engine problems

engine problem

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2002 Mitsubishi Diamante Owner Comments

problem #18

Nov 252010

Diamante 6-cyl

  • 91,000 miles


The heater core is an extremely dangerous problem. The windows in the car fog up so bad I couldnt drive the car...had to pull over and wipe the windows down. But the thing is...I didnt know what the problems was...until I realized the windows werent just being fogged by the cold, ect it was a toxic mist from a heater core problem...I pulled over 2 times because I got sick...I noticed a mist coming out of the all in all I called Mitsubishi and they refuse to do anything about this.this heater core problem can lead to accidents, sickness, and othe expensive problems in the car! the fumes are extremely toxic!!! there are 1000's of complaints and blogs about this problem...I'm sure there are 100,000+ complaints abpout this problem. And Mitsubishi refuses to help or do anything about this. I told them, is this gonna take a fatal accident for them to do something?" they replied, "im not answering that!" I told them that they should have recalled this problem. They replied, "sorry but your warranty is up we can't do nothing about it." This heater core problems leads to faulty transmission problems, electrical problems, hazerdous problems, sickness, interior of the car can be ruined because anitfreeze leaks through the dash board...where Mitsubishi placed the heater core. Made no sense to place a heater core above the electrical component of the transmission. They really messed up here and will not do anything about this. I think that the media should get involved because they probably wont do anything about if someone doesnt speak up!

- Freehold, NJ, USA

problem #17

Aug 012007


  • 80,000 miles
Just like everyone else with a 2002 Mitsubishi Diamante, I have had heater core problems. Antifreeze leaking/smell and windows fogging up. Cost to repair exceeds $1000. If every one of these vehicles has this same issue, why has it never been recalled" and why does Mitsubishi get away with all cars having this defect? and why has this investigation not resulted in action? is there another Agency that can get recall action from Mitsubishi"

- Fort Walton Beach, FL, USA

problem #16

Sep 192009


  • 60,000 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.

- South Bend, IN, USA

problem #15

Oct 152009


  • 30,000 miles


Heater core and O rings.

- Winthrop, MA, USA

problem #14

Oct 012008


  • miles
There should be a recall, own a 2002 Mitsubishi Diamante. I just found out that the anti-freeze smell and the smoke coming through the vents is because the heater core has gone bad. The quote I received was for $1100. My antenna just stopped working on me also. It doesn't go down anymore, but the motor still sounds like its working. We are all having too many of the same problems. The company should be liable.

- Jacksonville, FL, USA

problem #13

Feb 282009


  • miles
Windows fogged up, smell of antifreeze and carpet is wet on front passenger side.

- Sacramento, CA, USA

problem #12

Feb 022009


  • 74,000 miles


I have a 2002 Mitsubishi Diamante with less than 100,000 miles and already I need to replace the heater coil. I guess this is on going problem with Mitsubishi.

- Fpo, AE, USA

problem #11

Nov 152008


  • 95,000 miles
The heater core of the 2002 Mitsubishi Diamante needs to be recalled and/or redesigned by Mitsubishi. As it is, just about every single post I see online about this car has the exact same problem. The heater is positioned directly above the car's computer, or ECU, and therefore causing problems with the engine, transmission, suspension, etc.. the entire 80-page thread linked below is almost completely about this issue : there are many others like it. The issue is mentioned in technical service bulletins by Mitsubishi but is not recalled. People are buying this car used and having to replace the heater core (around $1200 repair).

- Richmond, VA, USA

problem #10

Sep 192008


  • miles
Heater core is leaking car only has 82,000K on the dash. As I have gone through various car forums and have come to realize this is a very common problem.

- Chester, VA, USA

problem #9

Aug 082008


  • 77,000 miles
I bought my car used from the dealership, and drove about 200 miles before I realized the antifreeze smell as well as my windows began to fog. After reading the vast amount of heater core problems in the Mitsubishi Diamante, I decided to file a complaint. Antifreeze in the cab of the car cold lead to health issues and the consistent fogging of the windows can lead to little to no visibility. The windows will randomly become intensely greasy with antifreeze backup, this can happen at anytime when I am driving. I am extremely concerned about getting into an accident due to my visibility, and am getting my eyes checked out just incase the antifreeze has affected them. Thank you

- Fitchburg, MA, USA

problem #8

Jul 312008


  • 20 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. My A/C turns on but nothing comes out sometimes. In the winter the inside of my car becomes a fog all over my windows and it wont stop fogging up. A smell is coming out of my vents like a coffee smell & im inhaling this smell whenever im in the car I have to go to a doctor to get checked out to see if I have health sun roof leaks when it rains, I took my car back to the dealer to have all these issues fixed but they never did I purchased the car in 02 the warranty lasted 02-05 B/C that is when my warranty expired. When I call they tell me I have to pay out of pocket B/C the warranty expired. This isn't fair to any Mitsubishi owner I shouldn't have to pay to have my car fixed now after the warranty when all the same problems have been recurring since I purchased the car and they never fixed it to begin with. I can understand if I was the only person with these problems I decided to search the internet to see if anyone else owned my make and model of my car to see if they had similar problems sure enough I came across a website called there's over 50 people with the same problems I have with my car.Mitsubishi should fix these problems and stand by there cars. I called corporate headquarters today & was told there's nothing they can do B/C its out of warranty.

- Wanaque, NJ, USA

problem #7

Apr 032007


  • 75,000 miles
Noticed faint smell of anti freeze approximately 9 months ago. Had problems with defroster clearing windows. Also, seemed to get better (or maybe I got used to the smell). Now noticed passenger side floor carpet is soaked with anti freeze. Obviously a problem with the heater core or the hose(s) which connect to it are leaking. Car has 92000 miles, and is well main.

- Erie, PA, USA

problem #6

May 022008

Diamante 6-cyl

  • 63,000 miles
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.

- Philadelphia, PA, USA

problem #5

Feb 042008

Diamante 6-cyl

  • Automatic transmission
  • 67,800 miles
The contact owns a 2002 Mitsubishi Diamante. The check engine light began illuminating, the heater coil was leaking, and the windows were steaming. The contact smelled a foul odor coming from the vehicle. A mechanic diagnosed that the heater core needed to be replaced. The failure mileage was 67,800 and current mileage was 67,990.

- Gardner, MA, USA

problem #4

May 012006

Diamante 6-cyl

  • 70,000 miles
Heater core leaking....check engine light came on....well known and documented problem with the Diamante....paid close to 800 to have repaired...coolant leaked on the computer and car went into fail safe driving mode.

- Snellville, GA, USA

problem #3

Dec 282005

Diamante 6-cyl

  • Automatic transmission
  • 47,890 miles
I purchased a used 2002 Mitsubishi Diamante in August 2005. The car had 45,000 miles on it. In October when I started to use the heater I could smell an unusual smell inside the car. In January of 2006 my brother rode in the car and told me the smell was anti-freeze. I went on the internet and instantly found out that this model car has a problem with the heater core O-rings failing. The smell in the car got real bad real quick and I had to have the leaking O-rings repaired. I would get sick from the smell and had no choice but to have it fixed. I brought the car to a Mitsubishi dealer and had the repair done for $650.the car had 48,000 miles on it when the repair was made. That is alot of money for problem that Mitsubishi should have corrected.

- Anoka, MN, USA

problem #2

Jun 102005

Diamante 6-cyl

  • Automatic transmission
  • 50,000 miles
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. The next day I noticed I was having problems again and checked the fluid level, it was low again. I knew something was wrong then and I took it to my mechanic. Low and behold I come to find out that the antifreeze, which is poisonous, has leaked all over passenger side floor and was told that it probably had been blowing out of the vents also. This was very disconcerting not just for the health of my wife and myself, but also because we had, at the time, a five month old who also had been breathing this poison. I pray we don't end up having any respiratory problems, especially my daughter, from this in the future. What ended up being the problem was the heater core corroded and was leaking into the car. My mechanic said this is not something that should happen to a car with only 50K miles. Actually, they said it generally should never happen to a vehicle. I come to find out that the leak is just above the cars computer system. Fortunately the leak didn't affect these electronic components. I see from the website that this problem is very prevalent and I'm sure it has happen to others that don't know who to contact about the problem. It ended up costing me $1300 to get it fixed. The problem lies behind the dashboard which ends up creating a lot of labor charges to fix the problem. I hope that there is something done by the ODI in response to this costly, unnecessary problem.

- Annapolis, MD, USA

problem #1

Aug 152004

Diamante 6-cyl

  • 55,000 miles
While driving engine check light will not illuminate. Vehicle stalled. Consumer took vehicle to dealer, and was told they could not fix the vehicle because the engine check light did not illuminate. Also, was told they replaced the crank sensor. Consumer took vehicle to dealer three times for the same problem.

- Philadelphia, PA, USA

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