Hey guys, I have a '99 2dr Blazer with both Cats gutted and I'm getting 2 codes. P0453 which I know is the Fuel Tank Pressure Sensor because its been on for over a year and I haven't got around to fixing it yet. The other is P0135 which I believe is the driver's side upstream O2 sensor. I gutted the Cats a few weeks ago and I was wondering if this could be causing the sensor to throw codes or should I just replace the sensor?

 

That’s your O2 sensors heating element. To speed up your injection system working more efficiently the O2 sensors are electrically heated so the system can go into closed loop as quickly as possible. It’s monitored by the on board diagnostics and sets this code when it fails. Your o2 is still working but is on its way out. The cat will eventually set a P0420, TWC below efficiency.

 

Thanks for the info man, I appreciate it.