PSA: Working evap system and/or catalytic converter not required to pass emissions.

[phucheneh]

I mean, I'm not telling people to cheat emissions...but I just figured I'd share that I'm absolutely flabbergasted at how I did not know that my county allows cars to pass OBD2 emissions testing without all the monitors being run. Especially since it's usually one stubborn monitor that keeps cars 'not ready' for an extended number of miles.

Even more amazing is that this appears to be in the federal EPA regulations; it's not based on individual state or county tests. Although it may be possible that some areas (...rhymes with 'Falifornia') may override this with stricter rules. But the EPA says: 1996 to 2000, you get two free passes on unrun monitors. 2001+, you get one.

Am I a 'tard for not possessing this knowledge? I vaguely recall hearing this years ago, but I think I dismissed it as outdated or incorrect info, and never heard about it or observed it afterwards. I've never dealt with any real issues on my own cars, and when I fix someone else's OBD2 vehicle, they generally run it through themselves. So today was a first for me seeing a 'pass' with a monitor listed as 'not run.':|

Anyhow, the reason this is interesting and useful (and kind of absurd)...the two most common 'emissions only' (generally not related to engine performance) failures are those dealing with the evaporative emissions or catalyst monitors. And guess which two monitors get run the most selectively (i.e. it's not hard to force them to run last)...yeah, those.

So, basically, if your 'check engine' light is coming on and setting an evap code...clear codes with the vehicle above the max 'cold start' temperature...evap will not run. Drive car enough to complete all other monitors. Run through emissions. Success? AFAIK, only evap depends on rather strict limits to engine temp; ECT must be inside a certain range that generally requires quite a long cooldown time to achieve.

If it's a catalyst code...do the cold start, drive the car around town...don't get on the interstate. IIRC, you basically just can't maintain speed with part throttle, as doing so for long enough will cause the somewhat-lengthy catalyst monitor to complete. I don't think any other monitor requires the same conditions to run, but I could be wrong. I've encountered numerous people with issues getting the catalyst monitor to run, though, and when questioned about their daily drive, the response is invariably something along the lines of 'It's not terribly long and I don't use the interstate.'

Anyhow, I'm done with my random babbling. I just thought it was interesting that our emissions testing, despite being relative strict, can easily be 'cheated.' On accident, even.

edit: and again, not intended as a "here's how to break the law" post. For one...it's not breaking the law; that's kinda my point, heh. But more importantly, I'm just curious if anyone else has any experiences to add and if this is indeed a nationwide regulation...

 

[NutBucket]

Yes, its quite lax on the federal level. Once you get to CA and a few other states, not so much.

I'll only get on my soapbox for a moment: I think CARB is a bunch of stupid government bureaucracy designed mainly as a source of income for the state. I digress....

 

[sontakke]

But there is a gotcha. If you go for emission testing and if you fail (or the system is not ready), now when you go back you can only pass if your CAT test is successful. So as long as you have a code reader hooked up which gives you the readiness status, you can time your inspection "just right" but it is still a gamble as when the light will trip if you indeed have issues with CAT or EVAP.

In a nutshell, you can NOT pass emission on a retest without cat converter test completed. You still have same number of incomplete test waivers but on retest the CAT can not be waived.

EVAP also runs only when the gas tank is between 3/4 and 1/4; so if you don't let tank drop below 3/4 you can "defer" the EVAP test from running.

OP told you when the CAT test runs. One way to defer it from running is to drive like a binary car or like a real maniac i.e. full gas or full brakes. The CAT runs at steady and gentle deceleration from highway speeds but if you slam on the brake at the exit ramp and floor on the entrance ramp on the way to the emission testing station, you would have prevented CAT test from running. Or you could actually fix it right (OEM converter) or fix it wrong (o2 sensor extension)