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Oxygen Sensors - bank 1 sensor 2

7K views 2 replies 2 participants last post by  thecthdox  
#1 ·
I just replaced my head gaskets and front engine cover (also called drive train cover) gaskets on my 2005 Ford Taurus flex fuel. As part of the process we had to disconnect the PCM. Now my car is burning through gas very quickly. In addition the check engine light came on. I took it in and the code read P2270 indicating that the downstream oxygen sensor in bank 1 was unresponsive and the lean test failed. My manual indicates that after plugging in the PCM. We should have performed a stop and go and highway drive cycle to reset the OBD-II system. Possible indicated solutions for the code include a bad connection or a bad sensor. I do not know what a stop and go or higher drive cycle are. Could someone explain? Also does anyone know how tight to get the PCM connection? It bolts e and I do not want to over tighten. Finally we did some work near the catalytic converter so it is possible we loosened a connection there correct? How do I tell which sensor is bank 1 sensor 2?
 
#2 ·
Read this post to understand what drive cycles and readiness monitors are all about

Drive cycles

Bank 1 is the bank that houses #1 cylinder. Sensor 2 is after the cat converter.

Think of the cat converter as an incinerator that burns off unburned fuel. The computer is constantly trying to find the correct air/fuel mixture for the speed and load. So it's constantly overshooting and undershooting fuel. The sensor in front of the cat sees rapid changes between rich and lean exhaust mixtures. When the air/fuel mixture is lean, there's extra oxygen in the exhaust and the precious metal in the cat absorb the oxygen--kinda like a bank account. Then, when the exhaust is rich, the cat uses that extra oxygen to burn it off. So the post cat sensor sees only a few changes between rich and lean and the swings aren't as wide. The P2270 code means it's seeing NO switching at all. Plus, it's reading lean. That can be caused by an exhaust leak, especially at the cat outlet. Can also be a connector problem.
 
#3 ·
I crawled underneath the car and found a lose connection near the oil pan. In order to replace the front engine cover gasket I had to pull the while oil pan off and replace the gasket. The connection must have come loose in the process or one of my friends who helped may have inadvertently disconnected thinking it was necessary. Anyhow, easy fix so thank you.