Rep Power: 0

My wife's 1998 Civic LX barely failed emissions today with a CO reading too high: 15.8679 vs the 15.0 limit. The HC and NOx readings were well under the limit. I'm thinking about just doing the test again and seeing if we get lucky, but am wondering if there is something relatively simple/cheap I can do first. The car does have 210k miles on it. Recent work done on it (by me):

New Air Filter
New Spark Plugs
New Thermostat
New Head Gasket, Intake & Exhaust Manifold Gaskets, Water Pump, Timing Belt

Any ideas? Thanks for any help!

Ryan

 
Rep Power: 812

did you drive the car til it was fully warmed up? at least 30 mins of town or 15 mins freeway during the summer. more in winter. if the car is not hot enough, the cat will be less efficient in reducing CO emissions.

 
Rep Power: 0

Thanks for the response gearbox. My wife drove it to the test, but I think it was only a couple miles from where the car had been sitting at her work all day. She did say that the temp gauge was up to its normal spot (just below the middle), but maybe that still wasn't good enough?

So you think if we just drive it a good distance and try it again we should be okay? It was barely over the limit - less than a gram!

 
Rep Power: 314

Give it a good highway run and it will pass for sure. I mean take it there right after your finished on the highway.

 
Rep Power: 812

yeah even when the temp gauge reads normal, the engine is far from optimal temp. the gauge is nowhere near accurate and is basically a loose cold/warm/hot gauge. car has to be driven at least until the cooling fans come on. im curious why they even measure emissions on 96+ year cars that have obdII. i thought they would just plug in the code scanner and if the engine light is off, you pass. i guess might be different in each state. but yeah even a brand new car would fail emissions testing (actual sniffer test, not obdII diagnostic) if it wasnt warmed up yet.

 
Rep Power: 0

Just wanted to let you guys know that our Civic just passed the emissions test with a ~11 CO reading! I had my wife drive it on the highway for at least 15 minutes before taking it in, and did fill up the tank with Premium gas (I read that idea elsewhere). So we are good for another 2 years (if the car lasts that long!).

Thanks for the help! Ryan...