Now at the point of taking this to a fiat garage .... unless anyone has more ideas. I'll try to summarise the last 2 weeks.

1.2 petrol Grande Punto

My wifes typical day is 3 journeys around 8mls each.

1) Last 7 to 14 days P0138 every day (can be 1 or 2 entries). This code always resets with the scanner fine. The car always drives fine - no loss of power or reduced fuel economy.

2) Last night removed the electrical plugs from both Lambda sensors and gave them a good clean with contact cleaner - left them open for 10mins to make sure were totally dry before putting back together. Quick test round the block and all seemed fine. The battery was disconnected for this.

3) Today during first car journey loss of power / fuel economy halfed. Checked with scanner and 1 entry of P0138 and 1 of P0171. Tried a couple of short runs and still power and fuel problem and many P0171's generated.

4) This afternoon picked up a NTK Lambda sensor and changed the post Lambda sensor (what P0138 relates to). Have tried various runs and no more P0138's, but still P0171 and loss of power and half fuel economy.

Hope that makes sense, checked for any cracked hoses but could not see any. A quick search says it could be the MAF, couldn't seem to find that.

Please help if you can.

Just wanted to let everyone know the outcome of these problems.

P0138 - fixed by me changing the post lambda sensor.

P0171 - created by me unplugging the sensor to clean the contacts. When I had the first fault (P0138) and cleaned the post cat lambda sensor, I also thought it would be a good thing to do the same thing to the pre cat lambda sensor. It seems I broke one of the wires internally as they are very fragile after years of being so close to the cat / manifold. What's the most annoying thing is that my code scanner did not show it as a lambda fault ..... just as running too lean (P0171).

Hope this helps someone at some time ...... be very carefull with these wires !!!