Following codes are from a reader that reads OEM GM ENHACNED codes labeled as FCS codes.

P0135:


Heated oxygen sensor (HO2S)
Heater Performance Bank 1 Sensor 1


P0172:

fuel trim system rich bank 1

P0401: this was the only code that was “stored”, it was the one that made the SES light turn on.

secondary air injection (AIR) system

first 2 codes I have no idea why they are on or what they refer to other then a googled description. The last code 0401 I’ve seen is just a typical tune of the computer to remove the AIR system, is this correct? I would as well have the EGR system removed. I have long tubes with an off road y-pipe no cats or no muffles with it dumped at the end of the driver side door.

thoughts?

just recently did MSD OTVC 8.5mm wires with NGK TR55-ix plugs, removed AIR, wrapped all the connectors from the pump into the harness. New mad coil, only fuel related thing I did was added raxetronix harness upgrade and wrapped some fuel lines by the y pipe.

thanks in advance for your help!

 

I would replace the o2 sensors but double check the current o2s to be sure they are seated properly(tightened) if they are tight replace them.

 

Both sensors have less then 3,000 miles on the combined. Both are oem parts from GM parts direct. I’m using front O2 extensions from WS6 store for a simple plug and play connection. I can try swapping the sensors with new ones, I’ve also seen a improperly mounted MAF sensor could cause it (meaning it’s backwards but I’m certain I have it right of all things but I’ll doubke check).

 

They were wrenched into the pacesetter bungs pretty snug with a dab of antiseeze on them.