I need to do a full reset on my XJR, but unfortunately I can't find my radio code. Since it's only the engine management ECU that I need to reset (just changed the H02S lambda sensor) I though I could just pull all its cables out and leave it a few minutes to discharge.

Is there a problem with doing this? Am I likely to get any security problems or something like that?

Thanks in advance

 

Why do you need to disconnect the battery for replacement of the HO2S???

A diagnostic computer simply clears DTCs and resets the ECM to P1000 with the battery connected and the ECM powered with KEY-ON-ENGINE-OFF.

Removing power from the ECM does NOT clear DTCs!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
The only thing it will do is erase P1111 and replace it with P1000 and leave the remaining faults stored.

You can remove the ECM fuse to reset readiness (P1000) but the HO2S fault will still be logged.

bob gauff

 

Also, it's risky to disconnect electronic modules with the battery connected, voltage spikes could cause damage.