One problem related to engine has been reported for the 2003 Mitsubishi Diamante. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2003 Mitsubishi Diamante based on all problems reported for the 2003 Diamante.
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.