2003 Mitsubishi Diamante Transmission and drivetrain Problems
- Complaints
- 4about this part
- Share
- 7%of 56 total for the year
- Median mileage
- 96,066miles
- Trend
- Not enough dataFewer than 15 complaints, too few for a reliable trend.
NHTSA recorded 4 complaints about the transmission and drivetrain of the 2003 Mitsubishi Diamante, 7% of the 56 complaints for this model year. Where a mileage was given, the median is 96,066 miles.
Fewer than 15 complaints name this part, so treat the figures as a rough indication only.
Example complaints
Selected from NHTSA records; personal details are removed. They are consumer reports, not findings.
“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.”
NHTSA complaint #10226354, filed 2008-05, 114,132 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! …”
NHTSA complaint #10224750, filed 2008-04, 78,000 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. …”
NHTSA complaint #10240783, filed 2008-09, 60,000 miles“The contact owns a 2003 Mitsubishi Diamante. The contact stated that the heater core fluid leaked onto the central computer and caused the transmission to fail. In addition, the gear shifter could not be released from third gear. The vehicle was not taken to the dealer. The vehicle was not repaired. The manufacturer was made aware of the failure. The approximate failure and current mileage was 164,000. The VIN was not available.”
NHTSA complaint #10502674, filed 2013-03, 164,000 milesRelated service bulletins
- 10170074Aug 28, 2015This is a service newsletter (Tech Talk) that was sent out to dealers.
- 10170071Jul 22, 2015This is a service newsletter (Tech Talk) that was sent out to dealers.
- 10170096Mar 5, 2013This is a service newsletter (Tech Talk) that was sent out to dealers.
- 10170100Feb 6, 2013This is a service newsletter (Tech Talk) that was sent out to dealers.
- 10170086Nov 1, 2012This is a service newsletter (Tech Talk) that was sent out to dealers.
- 10016754Jul 1, 20052-3 SHIFT FLARE.
Transmission and drivetrain: other model years
Other parts of the 2003 Mitsubishi Diamante
28 complaintsEngine cooling
17 complaintsBrakes
5 complaintsEquipment
3 complaintsSuspension
3 complaintsTires
3 complaintsElectrical system
2 complaintsFuel system
2 complaintsAir bags
1 complaintsExterior lighting
1 complaintsLatches, locks and linkages
1 complaintsSeats
1 complaints
← All problems reported for the 2003 Mitsubishi Diamante
About this data. Data from NHTSA (ODI) complaints, recalls, TSBs and investigations, updated Oct 31, 2026. Complaints are unverified consumer reports and may be duplicated or inaccurate.
To check a specific vehicle for open recalls, use its VIN at nhtsa.gov/recalls. Methodology