I took my grandmas pickup in and failed smog for the second time today

first time my numbers were

%C02 %02 HC CO NO
15 mph 12 4.2 23 0.03 661
25 mph 11.9 4.4 18 0.03 679



I found a cracked vacuum line to EGR valve and fixed with a bit of rubber hose. Sea-foamed my intake(through brake booster) and crankcase(1/2 can in oil), new copper sparkplugs and cleaned ERG with carb cleaner. Then a 10-30 synthetic oil change to get sea foam out of crank case after a couple days.

This time it passed the 15 mph part but still failed the 25 mph on the NO(ppm) section.

%C02 %02 HC CO NO
15 mph 11.8 4.5 23 0.03 601
25 mph 11.6 4.7 17 0.03 498

Anyone have any tips or advice to troubleshoot this? Guy at the smog place said 02 sensors fail every 60k miles but I'm not really sure that would affect the NO emissions.


Any help would be appreciated.
Thanks

 

That guy is full of **** I've seen stock sensors last 300,000 miles. No CEL? Your cat is probably bad Change your cat and it'll pass. Get a good one not an el cheapo. Magnaflow and flowmaster make great cats. I have flowmasters on my truck now they work great.

 

You aren't allowed to use aftermarket cats in California unless they have CARB certification.

High NOx is an excessively lean mixture, a defective EGR system, or a bad cat. It can also be excessive carbon in the cylinders or engine running too hot.

O2 sensors are cheap enough, it wouldn't hurt to change it.

 

Hey guys. I shelled out the 80 bucks for a diagnostic. Guys at the shop said it was a lazy 02 sensor. I let them throw one in for an extra hundred and the NO levels were low enough to pass. They ran it through at the shop and it passed by maybe 30 points. Not anywhere near the average but it worked. Grandmas pickup is smogged. Thank Zeus it wasnt the cat. upwards of 300 bucks for a new California legal one.