2009 2nd gen code P0402

I have a 2nd gen 2009 model, date of mfg. 1/2009 with 162,000 miles. After a series of repairs, I am still getting the P0402 code. This seems to point to excessive exhaust gas recirculation (EGR) flow except this model has no EGR valve or differential pressure sensor. For those that know the 2nd gen, exhaust gas recirculation is metered by the electronically controlled valve timing. My mileage is about 38 mpg although I am expecting more like 47 mpg.

I have:

• Changed oil, filter, and air filter
• Cleaned MAF sensor with MAF sensor spray
• Fully cleaned throttle body and throttle plate
• Replaced air/fuel valve (upstream O2 sensor) and downstream O2 sensor (both DENSO)
• Replaced PCV valve
• Replaced all 4 spark plugs with new

NOTE: Cat was stolen so I installed a $120 NON-California legal unit. Upon removal, both O2 sensors were caked with powdery carbon and the plugs were fouled.

The engine idles and runs fine, but I don't want to foul the plugs and O2 sensors again and would like the mileage restored. Is there anything that I missed that is causing the engine to run rich and making it throw this code? Any help is greatly appreciated.

 

Yes, positive. P0402 is the code. You may definitely be right about the cat. I've seen some posts about using an anti-fouling spacer or a resistor to trick the computer and eliminate the code P0420, but I'm getting P0402.