Check engine light – Code 4 (on plug itself – red light on diag. mod.) & Pin 14 CC/ET

[rwogs]

I just had the check engine light (CEL) come on again after haven driven about 600 miles since the last CEL incident. It gave a code 4 on the plug – red light on Diag Mod..
The diagnostic light on the modular plug under the hood on the passenger side of the engine compartment flashed “4” and then I put the home made code reader in pin “8” and got 1 flash…no fault found. When I put it in pin “14” it flashed “11” times. I did this twice to insure the code.
The “11” indicates --
“11 Closed throttle recognition signal to engine control module (HFM-SFI or Left LH-SFI) Fuel safety shut-off to engine control module (HFM-SFI or left or right LH-SFI)”
I believe that my engine contains the HFM-SFI
1995 E320 4dr Sedan W124 6 cyl auto., 90,000 mi.
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What in the world does this mean?

Is it serious?

How do I fix it?

I’ve been told that the O2 sensor usually goes bad.

Should I check the code on any of the other Pins?
I’ve left the code stored so that I can check other pins if necessary.

Thanks for your help