I keep getting O2 Sensor fault it is bank 1 sensor 2, which one is that. I have one on each manifold and one in back of cat anyone know which one is bad. I also am getting a EGR is insufficent code should I change it. Could the egr be causing the O2 sensor fault. My codes are 141 and 401. It is a 5.0 in a 96 f150.

 

I had the same codes, P0141 and P0401. Bank 1 is passenger side, sensor 2 is after catalyst, so it's the one in back of cat. Changing the sensor will get rid of 141 but not 401.

From what I understand the egr valves rarely go bad. You can do a quick and dirty check of the EGR valve. With the engine idling, remove the small vacuum hose from the top of the EGR valve. Get a small piece of tubing (like a foot of the small clear stuff you can buy at a hardware store) and put it on top of the valve and suck on it. If the EGR valve is working the engine will stumble or die, it doesn't take much. Or you can get a vacuum pump and apply a slight vacuum to do the same thing.

You can remove the valve and clean it with carb cleaner, PB blaster, WD40, etc. You'll probably want to replace the gasket (cheap) if you remove it though.

My 401 code was from a split in the bellows of the steel egr tube that runs from the bottom of the egr valve to the exhaust manifold. It took me forever to track that down. The bellows is just a few inches below the valve. Otherwise, look for any vacuum leaks in the system. I believe 401 can also be caused by a bad DPFE sensor or blocked or bad hoses that run to the sensor. Never messed with mine, though.

The insufficient flow could also be caused by blocked, carboned-up passages in the intake and throttle body. My next project is to remove and clean these when I replace my patched up egr tube with a new one. HTH

 

Thanks that was really helpful.

 

My 96 also had a cracked tube under the egr and the fiberglass cover. I repaired it but the code deturned . I ordered a new DPFE sensor . We will see if that gets it. Pat