NHTSA — Power Train: Automatic Transmission Problems


hardly worth mentioning
Crashes / Fires:
0 / 0
Injuries / Deaths:
0 / 0
Average Mileage:
84,044 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.

2003 Mitsubishi Diamante transmission problems

transmission problem

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2003 Mitsubishi Diamante Owner Comments

problem #3

Aug 092008


  • 60,000 miles


I own a 2003 Mitsubishi Diamante, around 60K miles I started noticing a sweet smell from the vents and a constant fog when the heat or air was turned on in the car. After taking my car to the mechanic I was told that my heater core was busted. My car also sdriving in "safe mode" meaning I can only run in second gear which is burning a tank of gas every three day, I love 10 miles from work. My car flashed in neutral will in drive. After researching my problems I've notice well over 1000 posted via internet from other Mitsubishi Diamante owners having the same issue. Its hard to believe this vehicle has not be recalled. There are great risks of inhaling anti freeze which is seeping into the car through the floor boards and vents. I have an asthmatic child who has been driving in the car until the problem was brought to my attention. This leak may also make the computer system in the vehicle go out. Something needs to be done before an accident is caused or a life is taken.

- Worthington, OH, USA

problem #2

Apr 282008

Diamante 6-cyl

  • 114,132 miles
My transmission relay went out due to a leak heater core. The core has been leaking for some time and has fogged my windows so bad I could not see at times, having to pull over and wipe off the film. This is a serious problem with these cars.

- Fallbrook, CA, USA

problem #1

Nov 282007

Diamante 6-cyl

  • Automatic transmission
  • 78,000 miles
I own a 2003 Diamante Mitsubishi. The problem started with a check engine light coming on, fogging the window with a fowl toxic smell then the car would not hardly move out gear. I was told that the car's heater core leaked onto the computer which caused the transmission relay to short out do to the computer failing. The computer was still under warranty at 78,000 miles but I still had to pay for the new computer system because I was told that it was the heater core that caused the computer to fail. This is such a poor design! the computer should have been protected in such a case...funny thing it is now that I have had to replace a heater core, a computer and a transmission relay at a cut wrenching cost of $3,675.58. I wrote a letter to the president of North America Mitsubishi that the heater core should be a recall but to no avail. I have all maintenance records on the Diamante so that was not what caused this heater failure. I do have the computer that was replaced. It is now April and the check engine light has come back on...now what?

- Nashville, TN, USA

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