Tips On Replacing Oil Pressure Sensor On 8.1l

mwitte · January 12, 2011

Hopefully someone here can benefit from my many hours of learning how NOT to do it. In the end if you do all of these steps the removal and install is maybe a hour. I am embarresed to even mention how much time I spent trying to start the sensor back in I was even comtemplating pulling the intake to get in there. The two things that helped the most were removing the fuel lines and the ground wire attached to the back of the head(15MM). The harness at least on my 'burb is what was killing me as I couldnt get the right angle to start it. Once I removed the ground wire and pushed it towards the passenger side it went in. Different cars may be different.

Symptoms was oil pressure gauge suddenly went to zero. No engine noise, so oil pressure appears to be ok just no gauge. My wife drives it so no idea how long it was doing this but if no oil pressure it would be dead.

1) There is a issue with the stepper motors in the instrument cluster on these but I was able to rule this out by testing the following

2) Using a ODBC scan tool I got code P0523(Engine Oil Pressure Sensor/Switch High). This does not set a MIL. Erasing the code then starting the truck caused it to go from 0-80-0 and set the code again. This kind of told me the stepper motor was working enough to drive the gauge.

3) By measuring the voltage at pin 58 on C2 tan/white on the PCM(oil pressure sensor input) I saw it was 4.5 V wjhich confirmed the code. Measure open to ground from here as well.

3) By removing the connector from the oil pressure sensor and turning ignition on it went to 80 and back to zero.

By this time I was pretty sure it was the sensor so I looked for some advice and had some hits saying just get a oil pressure socket down there and remove and replace. On the 8.1L its not quite that easy its a much bigger motor and very very tight. Also the fule lines as well as the harness run right over the sensor so there is no straight shot.

1) DO not use the oil pressure socket that fits the exact shape of the sensor i bought that first and spent a lot of time just trying to get it onto the sensor. It was just too tight and i could never get it on the sensor. Went and got a oil pressure socket that looked like a regular socket and literally got it out in a couple of minutes. Wasted a lot of time on that one. The sensor is pretty tight I was kind freaking out as its brass and if it snaps you are dead. Be really, really careful.

2) Do yourself a favour and remove the following or you will never, ever be able to get the new one in (at least if you have big hands), drivers valve cover, fuel lines (this will allow you to get your hand in once i did that it took like 5 minutes to get the sensor in), ground wire that comes out of big silver harness in the back(this was also preventing me from starting the sensor as it was in the way and once undone you can move the harness toward the passenger side). Once this is all out of the way you can easily get your hand in there and feel the hole. Another issue I had was that with the socket I really couldnt feel the threaded part and guide it into the hole. I rigged up a starter using a small piece of 3/8 fuel line. This fit over where the connector is. Then I used a spring type flex extension and wrapped some tape and fit into the fuel line. It was tight enough where i could turn it a could of threads to get it started.

3) Once sensor is started get the socket back down there and torque to 30N/M or 22ft/lbs. Put connector on and replace valve cover and fuel line and ground.

Started right up and I have 60lbs of pressure cold!

Next I am doing hoses and belts and idler pulley as there is some sqeaking. Belts are pretty hurting too.

speedracer0626 · January 13, 2011

Don't feel bad, jobs they were supposed to be 30 minutes always take me a little longer till I get the hang of what needs to be done. Atleast you didn't break nothing and there is always the fact that you did it and saved no telling how much money by doing yourself. Next time give us a step by step and pics for the other DIY people out there.