Hey guys

About 3 years ago I sold my 2005 ST170 to my neice, at the time the car was faultless and I'd had no trouble with it whatsoever whilst I owned it. I have just bought it back off her and have a few problems with it. firstly the MIL light is on and my neice tells me that it has been on for a while. The codes (P0135 & P0141) both relate to the O2 sensors internal heaters. Now my neice tells me that when the light first came on she had it scanned and the mechanic told her that it was the O2 sensors and he replaced them both and reset the light. However the light came back on more or less straight away so she took it back to the mechanic who scanned it again. He told her that it was the same codes as before so it must be a faulty ECU as the sensors were both new. As she was so skint at the time and couldn't afford an ECU and was also getting really poor MPG, she decided to park it up and SORN'd it. (This was last October)

I have just bought it back off of her as she is really skint and needs the money, and for some reason I felt responsible as I sold her the car. Anyway I have been scanning the forums regarding the O2 sensors and came across various posts which mention a fuse that tends to blow which can trigger the codes, so I checked the fuse and sure enough it was blown. I replaced the fuse and reset the mil light with my Bluefin scanner, and as soon as I started the car it blew again, and 2 more times after. Each time the mil light came straight back on with the same codes. Given the fact that both sensors were replaced recently and that this fuse keeps blowing I am guessing there has to be a fault in the wiring. The only problem is I have no idea which wiring to check or where the fault is likely to be. Obviously the first place to check is the O2 sensors connectors, however if these turn out to be ok what then? I would REALLY appreciate some help with this, as I dont have much money spare to spend on this. I am also clueless when it come electronics and have no idea how to use a multimeter.

The 2nd problem is a coolant leak from the thermostat housing, so I removed it to check and the rubber gasket/seal had perished quite badly and the plastic ring it sits in had cracked in 2 places. I have searched online for a new thermostat housing but can't seem to find one. So it looks like a dealer jobby unless anyone knows of where I might get one.

Also there is a weird problem with the guages in the cluster. When I turn the ignition off, the temp and petrol guages go down as normal, but immediately jump up to half way and sit there constantly. even with no key in the ignition. Any ideas?

Lastly there is a weird noise coming from the steering. It sounds like a kind of grumbling noise when turning the wheel. Again any ideas?

As I mentioned earlier I would really appreciate help with these issues, as I don't have much money and would like to fix as many of these as possible myself to save on mechanics fees.
Many thanks in advance!!