RPO Code Question (Page 1/1)
Mike in Sydney AUG 26, 07:54 PM
I was checking the RPO codes on my cars recently and noticed that one has code NA5 (Emission system, federal requirements) and the other has code NB2 (Emission system, Calif. requirements). So, obviously, one is a "California car" and the other isn't. Just curious, does anyone know the difference in the two?

RWDPLZ AUG 26, 09:43 PM
Not sure, but my federal emissions Fiero originally sold in Michigan passed California enhanced smog check in 2014 (with a new federal catalytic converter installed in 2005).
reinhart AUG 27, 03:15 AM
Absolutely no difference. CA RPO was an attempt to collect extra $ to recoup stricter emissions passed on to all Fieros.
theogre AUG 27, 03:45 PM
Many CA vehicles for late 70's and 80's have little or no change vs. "Federal" versions that you easily see...
GM and others had many OBD1 engines just w/ program changes to the PROM/MEMCAL to sell in CA.

Other cars had more changes you could see.
Example: Ford Pinto/Bobcat Carb 2.3l had 2 catalyst for CA. one under the car like Fed ones and second mounted to a "custom" Exhaust Manifold. Likely Had other changes too but not easy to see.

Can change carb design a little to a lot.
You can change many things in a Distributor too... Different Weights, springs or both in them changes timing curve. Can use different vacuum advance/retard parts too. They could change the Vac Avdance itself, change thermal valve(s) controlling that, even size of vacuum hole(s) on a carb etc connecting to the dist.

I'm not sure if Ford "variable venturi carb" was mainly to sell some cars to CA. That carb was a nightmare to many including to Ford Dealers. Has more problems now w/ E10 fuel.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

theogre AUG 27, 09:43 PM
Note for Non US Members... (Very Short Version.)

California has "Special Rules" meaning Exempt from US Federal rules for Vehicle Emissions because of several reason but mainly CA claims their rules are more Strict then Past and Current US EPA emissions. (Many In and Out of CA called BS for this Exemption even in the 70's but could fill many books as to why then and now.)

This is Why you see Two RPO codes above. Actual Codes can charge for given Model Year for One maker. Will change terms and codes between makers but means same thing so X = Built for Fed rules, Y = Built for CA rules, for that Model Year. Model Year like Business/Finance Years is Not a Calendar Year.

Worse, Some states like NY are moving or have made State's Rules to be more like CA.
NY forces new cars to meet most or all of CA rules.

That is Part of why is a push to Stop the Exemption for CA.
Car makers have a much harder time make product now that meets a Patchwork of Laws/Rules in many states half ass trying to be CA and Raises the price to make and means much higher price to you.

Similar issues can happen in other places...
X Country think needs odd emissions rules vs EU and other Big Markets but makers see little point making vehicles to meet odd rules for amount of units sold there. Already problems to make or import many models for Right Hand drive countries for same reason.

Is why Most of Canada's rules for new cars are near verbatim to US FMVSS. Has some different things like ECE cert Headlights are Legal in most or all of Canada.