Will disconnecting the battery reset the ECU, i.e. restore to default and loose error codes??

it wont get rid of errors i'm afraid ... ... - .- -.




Y. O. L. O.
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what error codes do you have  V8 facelift Range Rover Autobiography 22" wheels.
1976 Harley Davidson Iron Head Sportster

Don't have any codes, just the orange engine lamp. Local 4x4 garage stuck a machine onto the ECU plug & I was told O2 & HO2S sensors. They reset the light and it was fine for a day. I have replaced 4 of the O2 sensors, disconnected battery & light went out but came back on again 30 minutes later - any clues guys?

New development. Garage reset the error codes which only came up as O2 sensor 1 - garage used an autologic machine for landrovers. Light cleared but 30 mins later back on, garage who are independent LR specialists (ex LR) can't figure it out - anyone had similar experience?

I might need to buy a OBD, but which one will give the exact X1234 code?