Operator law enforcement was idling for an extended time in this vehicle. He was found unconscious in the vehicle and diagnosed with acute carbon monoxide poisoning. He was hospitalised for 4 days, and suffers continuing neurological deficits. Post-incident testing by engineer instructed by operator indicated two improper or incomplete welds on exhaust system, allowing exhaust to pool under vehicle and enter passenger compartment through HVAC fresh air intake. Post-incident testing recreated rising CO levels in passenger compartment. Vehicle has also been inspected by manufacturer. There were no warning lamps or messages.