The hardest part for most emissions test failure is proper diagnosis. What did you fail on? The test limits for an idle only test are generally consistent with all states for the year range of our vehicles. This limits are very high and are really only detecting gross polluters. The Waterboxer can pass this test even with the catalyst missing and with the correct basic adjustments a non-functioning O2 sensor. Properly working O2 and CAT the readings should be near "0". Many areas require the dynamometer testing as that puts the engine under load which tests the integrity of the O2 sensor and the 3 way Catalytic converter. For other vehicles this also tests the EGR system and other factors such as incorrect ignition timing can cause NOx production failures.

An ideal diagnostic test would be to test the emissions pre-cat. That is why there is a test port. With CO% of .04 you are running lean unless the CAT is working. With the CAT working you should not see HC of 69ppm.  You may actually have a lean mis fire causing the HC reading.

Dennis