Truck threw up 2 codes on me today. So I've had about 8 inches of my exhaust cut off about 6 inches in front of the muffler for about 6 months. Today, I took the muffler off completely and replaced it with a pipe. 1 in 2 out. Anyways afterwards I drove to the gas station and when I turned my truck back on my light came on.. Do I randomly just have two O2 sensors that went out or is this linked to having the piping put in and muffler completely removed?? I don't see how the 2 are related being that the muffler has been inactive but it's the fact that it was right after my muffler was removed that the codes came up that confuses me. Any thoughts or answers?? 4.2 engine

 

Really? You expect us to know what codes your truck is throwing? Hook up a code reader and figure out what the codes are. We aren't going to know whats wrong with your truck.
Wolvee might, but he's crazy.

 

Sorry, my mistake. I meant to put them down. 156 and 160

 

No power, something happend to the sensor while you were monkeying with the exhaust.

Check the rear O2 harness, drivers side. Look at the top of it, inspect the wires. If there's nothing visual, pull the connector and clean the insides real good with electrical cleaner. Has to be real clean, use compressed air to assist if you have it.

 

I'll check it this afternoon and see if the problem is solved

 

Yea, O2's, specially the rear can get lazy, The rears develop a hardened shell around the inside bottom of the sensor, where the gases spin around inside the louvered housing. Usually ends up being a switching problem (slow).

However you have circuit DTC's after removing the muffler. What's different, you changed up the restriction, flow and velocity. Although you more flow, you slowed velocity which is why you loose torque (just at low end) when axing the muffler, - and that's only because of the factory tune.

So yea, somethings up with the circuit somewhere, -check the wires/harness connector.

 

Finally got off my lazy *** and checked sensor. It had come disconnected by Laying on the exhaust and melting through the connector piece. Easy fix and plugged back together. Light went off