Since I bought my well-used 1992 Civic VX five years ago, it has passed Washoe County (NV) emissions testing with flying colors. This despite CEL Code 12 (EGR) and Code 48 (LAF) and the car having 237,000 miles on the clock. Also, the car runs great and has consistently delivered 40+ mpg around town.

Last summer it passed emissions testing so easily the station actually offered me a discount on the certification fee (something they are apparently free to do, but of course never do!)

Then, two days ago, the car failed the annual emissions test miserably. Suddenly it is emitting 3x permissible CO, and 2x permissible HC. Yet there has been no change in gas mileage (still 40 mpg) or performance, and no smoke or smelly exhaust.

I smell a rat. Is there even a remote possibility of test equipment error?

I now need to spend at least $200 to try to bring it into compliance, then, failing that, apply for an emissions waiver.

Can someone opine as to what could have deteriorated to cause the engine to belch 2x HC and 3x CO, without affecting performance or gas mileage, and without belching smoke?

Brian

 

Details on maintenance.

 

Update:

Smelling a rat, yesterday I trundled over to a different shop, call it Shop #2, and got a second emissions test. It passed easily.

In the lobby of Shop #2 was a chap who volunteered that he had a car fail emissions at Shop #1, yet also pass the test at a different shop.

So with the new test report in hand, I stopped by Shop #1 and confronted the mechanic on duty. He shrugged and said the state inspector had been there that very day and certified the test equipment. Assuming that's a true story, either the operator who tested my car somehow messed it up, or my car has an intermittent problem which caused CO emissions to triple, and HC to double, on a particular day, then revert back to acceptable levels two days later.

Brian