Cadillac Repair: service engine soon?, rear cylinder head, vacuum leak

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the "service engine soon" light is coming on with my 71k miles 92 eldo tc. is there a way to nail down the cause without taking it to the dealership?

thanks,
greg
Answer -
Hi Greg, Yes there is. With the engine running in park push the off and warmer buttons on the cliamte control for 5 seconds or until the display goes into diagnostics. Then write down all the P codes that are displayed. If there are any PP codes start with them first. To return the dash to normal just turn the key off and when you restart the engine the dash will return to normal. You will need a manual and test equipment to continue with the diagnosis process. If that seems too undaunting then you will need the dealer or another shop that speciallizes in Caddy repair or you could repost with the codes and I can try to point you in the right direction. Hope that helps. Bill

Bill,
Thanks. Here's what I see when pressing the buttons:

code E044 current
no IPC codes
no APC codes
no SIR codes
ECM?

Any ideas?

Thanks again!
Greg
Answer -
Hi Greg, The E044 means that the rear oxygen sensor is running lean. If it hasn't be replaced before there is a good chance replacing it might be all that is necessary to repair the code. Otherwise you will have to troubleshoot the engine why it is running lean such as a vacuum leak, restricted injectors, low fuel pressure etc. Bill

Bill,
Can you help me identify what this ogygen sensor looks like and where it is located?

Thanks again,
Greg

Answer
Hi Greg, If you look on the exhaust manifold where it comes out of the rear cylinder head you will see a silver cylinder alittle bigger that a sparkplug with probably 2 wires comming out of it. If you are unsure go to your local auto parts store and buy the sensor and then finding it shouldn't be a problem. You will need a special socket to remove and install the sensor and some places have loaner tools so you don't have to but something you might not need again. Auto Zone for example has loaner tools. Those sensors come out of the manifold easier when they sit for awhile...maybe a couple hours after you get home. If it doesn't cool enough you run the risk of stripping the threads in the manifold or having it sieze after comming half way out. Hope that helps. Bill