I have a 1996 blazer with a 4.3 vortec with tbi that has 2 codes in 401 and 1153. It is at the exhaust shop getting the exhaust fixed up and they are looking at the codes. My scanner just gives numbers and I thought I could just clean the egr and replace the O2 sensor and it would be fixed. The shop says it is a lot more in depth then that. They have the real good code reader and it tells them more then just codes it lets them know the actual numbers. But are they pulling my leg or are they onto something. I am sick of pouring money into this thing but I want it rite. It gets real bad gas mileage now and the shop says it is in limp mode.

Under the a/c unit on the intake drivers side there is some sort of, from what I can tell an egr tube with a check valve I think. It is metal tubing and sticks up but doesn't go anywhere. It is also crushed. My questions are what is it? does it go anywhere? Does it matter? Would it effect the egr flow?

 

P0401 - Exhaust Gas Recirculation Flow Insufficient Detected
P1153 - HO2S Insufficient Switching Bank 2 Sensor 1

Can you take a picture of the pipe you are talking about? The EGR supply pipe does not have a check valve in it. The AIR injection pipes do. If the EGR supply pipe is broke off and twisted shut, that is likely the cause for the P0401 code. It also is probably a vacuum leak that could be causing some running problems with the engine.

To diagnose the P1153 code properly, you really need to have a scan tool capable of displaying live data. You can try to shoot from the hip and replace the O2 sensor if you do not have access to such a scan tool. Remember, AC Delco O2 sensors!!

And your engine is not a TBI engine, but rather, a SCFI engine. It has multi-port fuel injection.

 

Here are 2 pictures of my question
What is it and does it go anywhere?

 

Based on the picture, it looks like this is the side on top of the engine behind the A/C compressor, if you look on the drivers side exhaust manifold where the manifold connects to the exhaust pipe 1-2 inches above the connection is the other side. I havent' had enogh coffee yet to remember the part #'s. Its the Exhaust Gas Recirculation, I just finished diagnosing the EGR valve myself. I have included the path and some pictures to help locate everything.