Well last week I scanned my car with my intreceptor gauge and I got:P0172 Fuel Trim System Rich , P2228 Barometric Pressure (BARO) Sensor Circuit Low Voltage, P0300 Engine Misfire Detected, P0107 Manifold Absolute Pressure (MAP) Sensor Circuit Low Voltage, P0136 HO2S Circuit Sensor 2, and P0140 HO2S Circuit Insufficient Activity Sensor 2. After I cleared all the codes the P0136 code has come back. I have no idea what is wrong with my car. Why am I throwing all these codes and not having any CEL come on?

 

The engine has to throw the code more than one time to set a CEL off. The computer still stores the code... but if the issue dosen't resurface in X number of driving cycles the computer will not set a CEL.

 

Put your mods back in your sig so we can see what your issues might be....

 

2.7,60's, header, 3inch catless dp, 3" cat back, K&N intake. Those are all the engine pertaining mods.

 

so if i put on a new downpipe with no cat will my check engine light come on?

 

Ain't that the understatement of the century...

yeah dude... it will...

 

^^^My down pipe has been on there for over 8 months but yes it will throw a Catalyst efficincy code. I don't get those codes anymore because I have an o2 simulator.

 

O2 simulator? please tell me more..........Sorry thread jack

 

^^Its pretty much just like a non-fouler plug. You install your o2 sensor into the simulator and then the simulator into the o2 bung. It pulls the o2 sensor out and farther away from the exhaust flow. This simulates the lower exhaust flow that you would have with a cat.

 

p0136 has to do with your O2 simulator. It wont set a mil unless it becomes more frequent.