I was under the impression that there was some kind of federal emission warranty law stating that all emission-related components had to be covered for at least 5 years. After consulting the Isuzu manual, I found out otherwise.

If you have a defective emission component replaced within the first 2 years or 24K miles, that replacement part is warranteed for 8 years/ 80K miles.

The only items covered for 8/ 80 are the cat and PCM. All other emission is 2/24.