code 41 and 42
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Tuned
Joined: Jun 2006
Posts: 420
Likes: 4
code 41 and 42
hey guys, i have a bit of a weird situation. i have a 1990 f150 5L and when i do a koeo test i come up with a 41 code (engine lean, and something to do with the O2 sensor not switching). however when i do a koer test i get a 42 code which is the complete opposite (engine running rich). so does this sound like my O2 sensor is on its way out? sometimes when i take off from a stop the engine flutters like it is missing for a few seconds then it takes off pretty darn good. i have installed full length headers and dual exhuast, and had to move the O2 sensor further back, so i had to cut the wires and made them longer (is this a no no?). just for kicks i disconnected the O2 sensor and took it for a drive, and nothing changed...i think it is the sensor but i would like someones input and any sort of tests i can do on the sensor or the harness. thanks in advance
Postmaster
Joined: Jun 2004
Posts: 2,665
Likes: 0
From: B/CS, Texas!!
Are you sure the 41 is a KOEO and not a CM code?
I would work on that KOER 42 first... check the fuel pressure at the fuel rail.. you need a fuel pressure gauge. Crank the truck and make sure at idle the pressure is around 35PSI.
I would work on that KOER 42 first... check the fuel pressure at the fuel rail.. you need a fuel pressure gauge. Crank the truck and make sure at idle the pressure is around 35PSI.
