Emissions Test Fail, CO front range

[amonostereo]

I've failed emissions every single time I've gone to re-register (every 2 years) for the last decade. The last few times, I've taken it to a mom-and-pop mechanic. Sometimes they get it to pass, sometimes not, but I always walk away about $2k lighter. (CO offers a 'repair waiver' after spending $715 in repairs)
Last time around they replaced the catalytic converters. I replaced a significant portion of the emissions system components a few years back trying to chase down the P0401 code, but never was able to quash it.
Anyone have some handy tips to pass emissions?
1996, 326k miles

 

[effjay80]

My sympathies just passed mine (94) up in Larimer County after a few years of failures. Alot tighter down your way.

My fix was a complete EGR redo = took off throttle body / manifold cleaned out all clogged passages, new EGR valve and modulator, all new vacuum hoses. Really wasn't all that hard or expensive and my main culprit was the gunked up passages in the throttle body and manifold. Been good since and hopefully fleeing the front range before need to do again.

Good luck.

 

[use2bn83]

You’re pretty darn close. There’s a ton of information over on the Rising Sun 4x4 club forum on chasing down emissions issues in Colorado.

Rising Sun 4WD Club Forum

Rising Sun 4WD Club of Colorado (Toyota 4x4) discussion forum

risingsun4x4club.org

Since you’re so close it might be worth extending your warmup cycle before going.

If you’re in Golden, put some premium in it and take a drive to Dacono test station early in the morning so you’re first in line. The long interstate drive will get things working.

P0401 is often the egr VSV, or modulator. But the IM240 test barely gets into the EGR ranges on our trucks.

OBD 2 Trucks have harder to pass standards unfortunately.

 

[Cruisers and Co]

Set timing to the stock 3 degrees btdc, fix your P0401, make sure your O2's are reading properly, make sure you don't have any intake/exhaust leaks. How old are spark plugs? May need an ignition tune up. We're the cats that were installed good quality? And if you need a hand we're in Westminster and happy to help!