osimic

Just changed the exhaust manifolds on my f150 4.6L and then re-torqued them. I get a P1151 code (lean O2 Sensor 1 Bank 2). The engine seems to run fine; any suggestions? Should I replace the O2 sensor on the drivers side before the Cat assuming I don't find any wiring problems?

plumberboy

I had same codes and many more after I changed my manifolds too. Many of my issues were vacuum leaks. Vacuum tube is cheap and easy to change. Are you sure the Egr valve passages are clear? If they are blocked you will not get the proper exhaust air mixture making a lean condition. When mine was blocked, it was so bad that when I opened the throttle body, used a flashlight I could see the blockage.
More things to look for, if the DPFE sensor is not working.... The Egr will not open enough causing a lean code. The tubes off the Egr tube to the DPFE being switched will mess things up.
The DPFE sensor is a piece of #^*#^. I bought one at advanced auto that did not work properly. Bought one at the dealership and it worked fine.
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