2001 BMW X5 pre catalyst fuel trim system

NASSERCO60

MEMBER
2001 BMW X5
6 CYL
4WD
AUTOMATIC
142,021 MILES

Dear sir I had a check engine light on my instrument cluster for my bmw x5 model 2001 I took it to the mechanic shop we had an error code dtc 236 trimming, oxygen sensor before catalyic converter, bank 2 the mechanic advised me to change the oxygen sensor befor the catalyic converter first
we brought a used oxygen sensor and replaced it after 350 miles the check engine light illumentated again I went back to the mechanic shop he said that he is not able to find any repair information about this dtc 236 because the bmw didnot give any informations about it pls advise me what to do or what is the possible cause of this dtc and if possible
or how to diagnosis this problem and solve it

1 Reply

DOCHAGERTY

MECHANIC
9,601 POSTS

A used sensor? Oxygen sensors are often at fault for the issue you are experiencing, I would recommend a new sensor and possibly both pre-cat sensors as they have a 100k mile life expectancy. Use only the Bosch sensor. Reset adaptations and drive until the readiness monitors are complete.