Most common 2001 Mitsubishi Diamante problems
Share of the 78 complaints; one complaint can involve more than one system. "~" is the median mileage when the problem started.
Mitsubishi Diamante complaints by model year
Best Diamante years: 1995, 1999, 1998. Years to avoid: 2002, 2001, 2003, 2000. Compare all years →
2001 Mitsubishi Diamante recalls (2)
Equipment › Other › Labels
Certain passenger vehicles fail to conform to the requirements of federal motor vehicle safety standard no. 208, 'occupant crash protection.' the bilingual english/spanish removable air bag warning labels affixed to the dash and to the sunvisor do not meet the size requirements of the standard.
Remedy: Mitsubishi caribbean will mail a customer notification letter containing a written description and a graphic of the bi-lingual dashboard air bag warning label.
Equipment › Other › Owners/service/other manual
Certain sport utility and passenger vehicles fail to comply with federal motor vehicle safety standard no. 225, "child restraint anchorage systems." the owner's manual does not contain a step-by-step description for headrest adjustment when installing a child restraint system (crs) tether strap.
Remedy: A letter outlining the problem will be sent to owners along with a sticker containing the correct instructions as well as instructions on where to affix the sticker in the owner's manual.
What 2001 Mitsubishi Diamante owners say
A/C & heater all 55 →
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). …
Purchased 2001 Diamante in September 2004. Had approximately 66,000 miles when purchased and approximately 73,000 miles now. At the time I purchased the car, I noticed a maple syrup smell in the interior, but I didn't know that it was an indicator of a problem so I didn't mention it, I thought it might be a cleaner that was used in the car. In December 2004, brought car to Mitsubishi dealer where car was purchased for a routine oil change and tire rotation. Was informed that strong coolant smell in interior (maple syrup smell) was from a coolant leak caused by broken o-ring which I was told by the service manager "happens in almost all diamantes". I told them that the smell was in my vehicle when I purchased it from the dealer in August and I believe they were aware of it at that time because they were able to quickly identify that same odor when I brought the car in for service. …
Engine & cooling
My heater core went on my automobile. The car is a 2001 Mitsubishi Diamante which has 50,000 miles on it. The problem started when the car had 45,000 miles on it, but I didn't know it was the heater core until later on. The dealer had the car for 2-l/2 days for a job that was 6.9 hours. I was told that the box that the core was in was either broken or couldn't be shut, but then they were able to close it, fix it I hope. I was told by another mechanic that it could have been the o-ring and that they had a car the same year with the same problem, possible recall. The dealer did a shabby job in replacing my dash board, I have 3 screws that I found on the floor, my glove compartment has a screw missing, none of which I have in my possession fits the missing screw hole. When I picked up the car, the steering column came apart in my hands and so they took it back in to fix. …
My car is making me sick. I purchased my car in aug. 2001 and began to notice a smell in the car and fume closely resembling that of radiator coolant. The car was assesed by a Mitsubishi district manager and service personnel from my dealer and deemed to be sound. In the mean time I have suffered with runny eyes and intermittent paralysis in the right side of my face dependent on the amount of time spent in the car. I have contacted Mitsubishi numerous times about this and received no assistance. In November 2004 I noticed an increase in this smell and fogging problems of the interior windows. I took the car to the dealer telling them that I believed the problem was with the heater core. I ascertained this information through internet research dealing with Mitsubishi Diamante defects and problems. …
Transmission & drivetrain
I have a 2001 Mitsubishi Diamante, and am having problems that seem to run rampant among this model/make. My heater core went out at about 100K miles; my ABS light stays on (due to a speed sensor fail), which renders the whole anti-lock system useless; and now my antenna mast is broken. All of these problems are pricey to fix, and most Diamante users I have found experience at least a few of these conflicts. Another problem I have seen many comments about is transmission failure at 113K miles. My car has exactly that. On top of everything, it is winter, and anti-lock brakes are much preferred in icy weather. I am starting to smell antifreeze again, the warning sign to a failing heater core, which can leak onto a transmission computer and cause it to fail as well. I am beginning to worry about being stranded, and even being safe in my car. …
1) smelled antifreeze but could not find a source. 2) heater coil was leaking. 3) leaked on a computer that controlled my transmission. Why would anyone place an electrical part under a unit that hold a liquid? Why would the electrical part not encased in a protective wrap if it had to be placed next to a pressurized liquid carring coil? 4) I was charged $1,125.00 to fix a problem caused by sorry engineering. I learned that misubishi knew of the problem and never notified their customers. There should be a recall and Mitsubishi should have to pay for the repairs. All parts, heater coil, transmission regulating computer were replaced.
2001 Mitsubishi Diamante engines & fuel economy
| Engine | Transmission | Drive | MPG city / hwy / combined |
|---|---|---|---|
| 3.5L 6-cyl | 4-speed automatic | FWD | 16 / 23 / 18 |
EPA ratings. Class: Midsize car.
Frequently asked questions
Is the 2001 Mitsubishi Diamante a good car?
Based on 78 owner complaints filed with NHTSA, the 2001 Diamante rates avoid: 2.5× as many complaints as a typical year of the Diamante at the same age. It is one of the Diamante years we suggest avoiding. Complaint counts don't account for sales volume or individual maintenance, so have any used car inspected before buying.
What is the most common problem with the 2001 Mitsubishi Diamante?
The a/c & heater — 55 complaints, 71% of all complaints for this model year, most often about defroster/defogger/hvac system › heater core. Next are the engine & cooling (14) and transmission & drivetrain (4).
How many recalls does the 2001 Mitsubishi Diamante have?
There are 2 recalls for the 2001 Mitsubishi Diamante, the most recent from September 1, 2004 (labels). Recall repairs are free at any authorized dealer — check whether yours has been done with the VIN recall check.
What are the best and worst years of the Mitsubishi Diamante?
The best years by complaints, compared at the same age, are 1995, 1999 and 1998. Years to avoid or approach with caution: 2002, 2001, 2003 and 2000. See the full Mitsubishi Diamante years comparison.
At what mileage do 2001 Mitsubishi Diamante problems happen?
The median mileage reported in complaints is about 60,000 miles; 37% of problems with a recorded mileage started before 50,000 miles.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) — owner complaints through October 20, 2026, recalls and defect investigations; fuel economy from the EPA. Complaints are unverified reports and are not proof of a defect. How we rate model years.