2002 Mitsubishi Diamante LS from North America - Comments

Well, I did it. The 2002 Diamante with the heater core gasket problem was exactly the same as many others have reported. Over the course of a couple of months, I carefully followed the 21 step process and replaced them myself. After finishing this procedure I am relieved that there is no more leak and the check engine light is off.

Takes a lot of patience...

I purchased my 2001 Diamante new and have 61,500 miles on it. I had the same O ring issue at 31,000 miles. However, since it was past the five years by one month, I was told it was out of warranty.

Two weeks ago I did the 60k service, which included replacing the timing belt, flushing the transmission and coolant. I planned on keeping the car for a very long time so I did all the suggested maintenance. The transmission failed last week while driving without any warning. I spent many hours on the phone and as you can probably guess, Mits would not give any assistance or consideration since it was out of warranty, even though all the maintenance had been completed. I had to come up with $2,500 to put a rebuilt transmission in the car. The shop indicated these transmissions have a problem with the chain breaking and being sucked up into the pump, causing failure with no warning.

I also had a small rust issue on the right rear quarter at around $50,000, but I was educated by the dealer and the rep and told it was not rust. Even if it was, since it wasn't through the metal (I'm assuming since I could not poke my finger through it) it would not be covered. Three claims, no help at all.

I can't even begin to tell you how disappointed I am. After reading all these comments, it appears these cars have both defective heater core O rings and transmissions. I expected much more from my first new car ever and one I paid $28,500 for and have taken care of. I called a friend of mine last week since he has a 2002 Diamante to warn him. He advised the transmission went on his Diamante last year at 85K.

This will be the last Mits. I will ever buy.

I added the above blog, and after a few days of getting my car back with the new transmission, the TCL light and the anti-lock brake light went on. The TCL flashes and the anti lock light stays on. It appears from reading above it is a wheel sensor. Can this really be happening???

This is the third major problem that everyone else has listed above. Is it possible the shop damaged a wheel sensor when they worked on installing the new transmission? Anyone qualified to give me their opinion?

It seems like too much of a coincidence. I'm having the shop scan it on the machine to determine the cause and what wheel if it is a sensor. If it is the sensor, how did the person above get this fixed for $200? Please respond if possible.

I just found out it is the right rear wheel sensor that needs to be replaced. Any idea on how it could be replaced for $200 as mentioned above? The dealer quoted me $454 for just the sensor? It doesn't appear there is much labor involved. Do they make an after market sensor? Help?

Another 2003 Diamante heater core victim. Replaced the O ring for 1000. Wish I found this blog before purchasing this car. Mits should at least offer me a free oil change.

Good luck trying to get an oil change from them. Not sure how many miles you have on your car has, but I would start saving money as it probably won't be long, and your transmission will fail at a cost of $2,500, and you will also have the TCL/Anti lock brake light go on for another $700-$800. I hope you have better luck than I did.

No transmission failure yet, 59,000 miles... knock on wood.

Two problems so far on my 2002 LS, which I bought new in November of 2001. Four months ago the Traction Control light came on. I took it to my local mechanic and he changed the right rear sensor, which fixed the problem ($600 total). Two months ago the Service Engine Soon light came on. I checked all fluids and installed a new air filter but the light stayed on. Took it to my local mechanic and he changed one of the oxygen sensors, which fixed the problem ($400 total).

I quit using the Mitsu dealership when my warranty ran out. They wouldn't fix a sticking accelerator pedal because I wouldn't adhere to the dealership's schedule of maintenance, which was far beyond Mitsubishi's schedule in the owners manual. They contended that I had allowed a build up of varnish in the throttle body and that was making the accelerator pedal sticky. I took it to my local mechanic, he lubed the linkage cable and it fixed the problem. I did protest to Mitsubishi about the dealer's unfair practices and they were reprimanded and have since closed up shop.

I just installed an air horn on the car and now the OEM horn won't work. The fuses are good as well as the relay. I might have screwed up the contacts in the horn button. I'm not going to mess with it though as I'm leery of setting off the air bag.

I love my LS and would like to find a very low mileage 2004 that is not black. I like the tan/cream color best.

My A/C is working fine but I cannot get the A/C to blow through the center vents. It will blow from the top (defroster) and the bottom vent. Any suggestions to this problem? All the controls seem to work fine. 2002 Mitsu Diamante.

I commented above on March 24th with the transmission problems and the April 7th and 8th. I can tell you exactly what the problem is, as this was another problem I had. This is a very easy fix. There was a bulletin sent out by Mts regarding this problem and how to fix it as this happened on my 2001. There is some linkage that opens and closes the door that allows your A/C to go to the different vents. They simply need to add a screw or something to hold the rods together. I would check with a dealer to pull the bulletin. It was a simple fix and I was not charged for it. KM.

Our 2002 Diamante heater core went out at about 60,000 miles. A couple of months later the Neutral light started flashing when I put it in drive, the transmission seems like it won't engage. The car won't shift. diagnostic says Automatic Transmission relay - we replaced that and still have the same problem. Now stating it might be a loose wire or the computer!!!

HAS ANYONE SERIOUSLY CONSIDERED A CLASS ACTION LAW SUITE? AFTER READING ALL THESE POSTS, AND IF NOONE HAS DONE ANYTHING TO GET ONE STARTED, I WOULD BE WILLING TO DO THE LEG WORK... LET ME KNOW.

It sounds like your computer control was damaged by the leaking heater core. This is located directly under the heater core. Welcome to the Club of defective design and parts by Mits. KM.

I bought a 2003 before I read this listserv. Too bad. Now when I pull back the passenger side carpet I see no moisture but a lot of green powder. There is the faint odor of antifreeze too. I ran the car for 1 hour (heater at 90 degrees) with the carpet pulled back and saw no drips or vapor. Windows don't fog either.

Is there any place to look to see if the problem may have been fixed? I guess if I can't determine if it was fixed, I'll replace the gaskets just to be sure.

Is the TCU ECU in the main ECU below the heater core? My tcu off light comes on after a few minutes whether I am driving or not. All wheel sensors are OK and the ABS works so the TCU-ECU is suspect. I just can't find a separate box.

I'm not too happy with this Diamante. My 94 went 22K before I gave it away.

The green residue you see around the passenger side carpet, along with smell of burnt maple syrup, are the tell tail signs that either the heater core gasket was or may still be leaking. Are you able to contact the previous owner to find out for sure if it was fixed? I have an '02 VRX and repaired my own leaking heater core last fall. It's not that hard to do it if you mechanically handy, and doesn't require tearing the whole dash out like the dealer charges you $1000+ to do. One thing going for '02 and later model owners is that Mits. starting putting a plastic wrap around the Powertrain Control Module (PCM) that is right under the heater core pipes, no doubt cause they knew had a leakage problem and didn't want to fix it right way.

One way to find out if there's still a leak is to clean up the carpet of all green residue and the smell as best you can (try baking soda). Pull the carpet up and away from the floor board and dry out the area underneath as well. Periodically check that area to see if any residue or moisture reappears. The leakage can be slow as to be hard to detect by inspecting the coolant overflow bottle level. Check above for link to the step by step procedure to do it, or I can repost on this website.

Hard to say if the light coming on is related, but you can go into any shop (may have to pay a diagnostic fee) or auto parts store (for free usually) to have them read the codes for you. That will at least tell you where the problem is.

I had a bad rear wheel ABS sensor that was turning my ABS/ TCL light on and off. Took a sensor off a late model Diamante in local junkyard and replaced it myself for $150. Dealer wanted $550 do do it. Right!

Once the two above biggest and potentially most expensive problems with this vehicle are fixed, it runs just fine. Good luck!

I also own a 2002 Diamante and just spent $1500 to have the heater core replaced and now my A/C does not work. The garage said it will be another $1300 to get a new evaporator core.

Did anyone look into any recalls on the heater or evaporator core? This is ridiculous that we are all having the same problems and Mitsubishi hasn't done anything about it.

In order to repair/replace the heater core, you have to disconnect the A/C lines from the engine compartment to the evapaorator, evacuate the refrigerant, and remove the evaporator unit itself from under the dash. I know cause I did this repair myself on my 02 VR-X last year. I'd say there is a high likelihood that the shop that repaired your heater core may be responsible for you're a/C system not working, possible due to damage caused, misassembly, lack of adequate or leaking refrigerant during the heater core repair. I would go back to the shop that replace your heater core and asked them to explain this strange coincidence.