2003 Mitsubishi Diamante LX 3.5 from North America


Heater core blew out at 65,000.

Engine always died at 95,000! Cost 1000$ to fix!

Transmission went out at 12,000.

Electrical started smoking and wires burnt up at 150,000.

Too many problems. We will never buy Japanese again.

Would you buy another car from this manufacturer? No

Review Date: 18th March, 2011

2003 Mitsubishi Diamante LS V6 350 from North America


Love my Diamante, and would buy another in a heartbeat!


I could and still can hear the antenna motor, but a screwed on antenna was on it when I bought it, I didn't notice it at the time that it should have a retractable one.

Transmission went out at 75,000 miles or so said the transmission shop. Cost 2,600.00 and the light is still on and the car creeps from 1st gear to 2nd, then runs like a bat outta hell. After reading the comments, I see that it may have only been a relay switch that got wet when the heater core started leaking at 70,000 miles.

I love this car, I've had it 7 years and it has cost me nothing compared to the Fords and Chevys I've owned.

I heard that Mits. was making another Diamante for 2007, and was very disappointed that they did not.

I didn't realize the heater core problem was world wide with the car. I'm getting ready to have my personal mechanic replace it, and I hope it doesn't go out again.

I need new struts and shocks as well, but I've driven this car long and hard with only these 2 problems. I say "Bravo! to Mitsubishi for that".

All the windows and seats still work, the leather is great. No cosmetic problems like I had with Ford and Chevy. Matter of fact my daughter has a 2003 Chevy with half the miles of my Diamante, and we replace something every other week!

General Comments:

The engine is awesome! Runs like a top.

I use only synthetic oil and premium gas.

Would you buy another car from this manufacturer? Yes

Review Date: 20th April, 2010

22nd Jan 2011, 19:36

I would love to know what kind of gas mileage you are getting on this car, as I drive one myself, and I am getting 22.5 miles to the gallon on regular gasoline.

2003 Mitsubishi Diamante VRX 3.5 from North America


I too have replaced the heater core on my 2003 Diamnate VRX at 65,000 miles. Also, timing belt. Now the transmission has gome out at 87,000 miles. I wonder if there is something to the tip that perhaps the radiator fluid leaked on to the Transmission Control Unit? I like the car but I should not have to replace a transmission on a car with less than 100,000 miles. Mtsubishi? Never again.

Would you buy another car from this manufacturer? No

Review Date: 11th November, 2008

17th Dec 2008, 13:59

I too have had to replace the heater core and replaced two transmissions. The car is a very beautiful looking car, but there are numerous problems that should not occur less than 100,000 miles. I am just hitting 68,000 miles and these problems are happening. I would NEVER purchase another Mitsubishi again!

1st May 2010, 01:24

I bought a 2003 Mitsubishi Diamante LS. (Mitsubishi never again!!!) I repaired the "infamous" heater core leak myself at about 70K miles. Now, at 82K miles, the transmission is acting up. It very slowly engages into reverse and won't engage into drive unless you give it some gas. Took it to a transmission shop 7 weeks ago. Installed a used transmission and it didn't work. Rebuilt my original transmission and still does the same thing. I asked if it was the transmission control unit (TCU). The transmission tech says the 2003 year model did not have a TCU. He said it is all contained in the Powertrain Control Module (PCM). The PCM seems to be working fine. We can't figure out what's wrong, and my transmission tech and I are getting very frustrated. Any help would be appreciated.

18th Jun 2010, 00:11

It is quite funny. Seems that Americans get all the problems. And the OZ and NZ market get great ones.

Mine has never had the heater core.

The timing belt is always needing replacement. And at that miles that is normal. Should be done any way.

As for the tranny, if driven normal and very well serviced, you would never get any issues. Mine was junk, but had never been serviced. Now that I have had it rebuilt, it is the best I have owned. Thrashes any Toyota 4 speed tranny.


17th Jan 2014, 07:42

I have this problem and need help fixing it. Any fixes yet?