2003 Mitsubishi Diamante Engine cooling Problems
- Complaints
- 17about this part
- Share
- 30%of 56 total for the year
- Median mileage
- 60,000miles
- Trend
- StableComplaints filed in the last 3 full calendar years are within 25% of the 3 years before.
NHTSA recorded 17 complaints about the engine cooling of the 2003 Mitsubishi Diamante, 30% of the 56 complaints for this model year. Where a mileage was given, the median is 60,000 miles.
Example complaints
Selected from NHTSA records; personal details are removed. They are consumer reports, not findings.
“I purchased a used 2003 Mitsubishi Diamante from bankston dodge in 2007. It was clean and ran well. There was an unusual odor inside, but smelled as if it could have been what the dealership used to clean the inside. It turned out to be anti-freeze. The vehicle had a heater core leak prior to our purchase. Recently the gas gauge has stopped working.”
NHTSA complaint #10276190, filed 2009-07, 50,000 miles“I have 2003 Mitsubishi Diamante. My check engine light came on, so I took it in for service, and my heater core was leaking on my computer...now it's going to cost me around 3,500 dollars....this is a very flawed design. There should be a recall on this item.”
NHTSA complaint #10223524, filed 2008-04, 20 miles“I have a 2003 Mitsubishi Diamante with 60,000 plus miles. For the past several months I have noticed a strong smell of anti-freeze coming from the vents and the windows constantly fogging up, sometimes to the point that I cannot see to drive. I have read many similar complaints and agree with others that Mitsubishi needs to issue a recall for the heater core, as I am sure this is the problem. I have yet to take mine in to get it repaired, so I don't have a cost quote at this time.”
NHTSA complaint #10318872, filed 2010-03, 62,000 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.”
NHTSA complaint #10226354, filed 2008-05, 114,132 miles“This is a Mitsubishi Diamante 2003 es. I'm experiencing a sweet smell of anti-freeze inside the car as soon as I turn on heating. Anti-freeze contains ethylene glycon and the fumes are highly toxic. Fixing the heater core will cost $1300. …”
NHTSA complaint #10211220, filed 2007-12, 86,000 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.
- 10170086Nov 1, 2012This is a service newsletter (Tech Talk) that was sent out to dealers.
Engine cooling: other model years
| Year | Complaints | Share of year |
|---|---|---|
| 2003 | 17 | 30% |
| 2002 | 38 | 31% |
| 2001 | 14 | 18% |
| 2000 | 7 | 14% |
| 1999 | 3 | 13% |
| 1998 | 1 | 4% |
| 1997 | 4 | 12% |
| 1995 | 2 | 17% |
| 1994 | 2 | 7% |
| 1993 | 3 | 10% |
| 1992 | 11 | 26% |
Other parts of the 2003 Mitsubishi Diamante
28 complaintsBrakes
5 complaintsTransmission and drivetrain
4 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 29, 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