OBD Error code P2021 on 2005 Outback 2.5

[kiter]

Hey folks my 2005 Outback 2.5 auto has the EML light on and is running poorly and fuel economy gone down the pan. All started after I replaced the air con compressor. Have checked the connections for the TGV and seem to be ok, thinking I had knocked something when working on it. Any other suggestions - doing my nut trying to sort this and car an MOT at the end of the month so need to get to the bottom of it. Any advice welcome. Thanks in advance.

[Greenmamba]

This may help.

http://www.obd-codes.com/p2021