97 BMW 740IL - 4.4L V-8 Engine - Scan Codes PO420 and P1384

hustler57 · **Joined:** Wed Jan 21, 2009 4:30 pm **Posts:** 1

Scan revealed Code P0420 = Catalyst System Efficencey Below Threshold (Bank One) and
BMW Specific Code P1384 = Knock Sensor 3 Circuit

Could this problem be the Oxygen Sensor or is it a problem somewhere else in the system? Any help will be appreciated.

Sponsored Links · **Joined:** 29 Jun 2004 08:12 pm **Posts:** N/A

Mohawkmtrs · **Posted:** Thu Jan 22, 2009 9:41 am

Forget the O2s...chances are it's the cat that needs replacement (Bank 1). After all, it is 12 yrs. old.

Make sure you get a good quality cat or else you'll be replacing it often. With cats, you get what you pay for.

After the cat replacement and codes are cleared, check and see if the P1384 comes back.

If so, check wiring and connection to the sensor as well as the sensor itself.

Good luck and keep us posted.

97 BMW 740IL - 4.4L V-8 Engine - Scan Codes PO420 and P1384

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