Codes P1131 O2 and P1152? How could it be running lean and rich at the same time?

OVERHEATING

MEMBER
1999 FORD F-150
4.6L
V8
4WD
AUTOMATIC
200,000 MILES

I replaced the o2 sensors about a month ago because I was getting a rich code and could not find a cause, it seamed to solve the problem for about a month, now I am getting P1131which is bank 1 running lean, but I am also getting P1152 which is bank 2 running rich, where do I start to diagnose this issue?

Sunday, August 7th, 2022 AT 10:40 AM

1 Reply

KEN L

MASTER CERTIFIED MECHANIC
51,478 POSTS

The P1131 code is lean bank one and P1152 which is bank 2 running rich, so this is because on bank 2 the system is running rich so the computer tries to lean it down to be within limits, but it can't, so it goes to lean and bank one is affected. So, on Bank 2 you have an injector that is stuck open or dirty, to find out which one pulls the plugs on bank 2 and one of the plugs will be dark/black this is the cylinder that needs a new injector, (and spark plug).

Here is a video on how to change the injector out:

https://youtu.be/MtSfOhZYqYM

Please let us know if you need anything else to get the problem fixed.

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Monday, August 8th, 2022 AT 10:32 AM