2000 Discovery II - code p0600- no blinking m/s lights- limp mode

Lawless Creek

New member
Feb 8, 2022
Central South Carolina, USA

If there is another thread that will help, please let me know.

P0600 – Serial communication Link.

Oxygen Sensor circuit No Activity

2000 Landrover Discovery II

Stuck in limp mode, no blinking m/s and 3 amigos come and go. When I unplug the TCU under seat and start, m/s start to flash, plug it back in, they go away. I have not done anything with the XYZ switch. Could that be the issue? I did sink it pretty good and the TCU got a little wet. (no corrosion on plug) I opened all the doors and I let it dry for a couple of days, ran normal for a couple of miles but then went into limp mode and now stays there. ECU did not get wet. Since the m/s lights aren’t blinking not sure what else to check, other then unplug, clean and re- plug all connections. Would the O2 sensors do this?

Things I have done:

New battery
Alternator checked at: 13.7(under load) 14.1 idle
Changed transmission fluid
Changed diff fluid
Checked fuses
Checked all grounds I could find. (Alternator, and the one that goes from fuse box down to frame. Are there more?)

Have great day!


Well-known member
Apr 24, 2004
If your TCU got a "little wet" I would start there.
I got a tcu a little wet in my 2000 that didn't show signs until the next morning. Pulled it out took the case apart and flushed it with WD40 and I never had anymore issues with it.