1995 3.8 throwing lean code on right bank only.


New Member
Dec 25, 2020
First off, let me say that yes, I have searched the threads. In fact, I sent a lot of time searching threads when I first got the car, as it had right and left bank lean codes that would return within 15 miles after clearing. I traced that to a broken vacuum line. When I fixed that, the heater started working properly (the broken vac line was the one to the heater control switch), the rough idle smoothed out, and it stopped throwing any codes for a couple hundred miles. I thought I was home free.

However, in the past couple hundred miles, it gives a "right bank lean" code about every 50 miles. It runs fine, no roughness to the idle. Clear it and it stays gone for about 50 miles.

The snapshot does show the right bank fuel map at about 24. I looked for a leaking intake gasket when I was chasing the initial problem (carb cleaner) and found nothing.

I have not yet checked fuel pressure, but I am reluctant to think that this could be the cause, since the code is consistently to one bank only. I am thinking perhaps an upper or lower intake gasket leak, or an O2 sensor issue. I am thinking that I should maybe replace the O2 sensors just because of age, anyway.

Anyone have a similar issue, or just know more than I do?
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