Engine problems

[Andy111]

I've got a couple of problems with my car - S2 111S.
When starting the car from cold it stalls, once it is warmes up a little it idles at about 600rpm.
I also get the engine warning light coming on, I have cleared it but it comes back on after a while, the two error codes I am getting are:
P0132 O2 Sensor Circuit High Voltage (Pre Catalyst)
P0138 O2 Sensor Circuit High Voltage (Post Catalyst)
Does anyone have any ideas what might be causing the problem?
Thanks
Andy

[Gad-Westy]

On the S1, the throttle pot can cause problems like this and can be reset by a procedure that involves pumping the accelerator several times with the key on position 2. Have a flick through your manual (or a google search) to see if it can be done on an S2. Good first port of call.

Other than that, it may be worth checking that your earth and alternator connections are ok.