O2 / Maf Sensor, Fuel Trim Fault Finding

[winelight]

I have "P0171 Fuel trim too lean (bank 1)".

Inspection of the live data reads:

MAF sensor reading - steady (I believe this means the MAF sensor is probably working OK and does not need cleaning?)

O2 sensor reading - fluctuates between about 0.1V and 0.7V (I believe this is normal operation at idle)?

So, I am stuck to know what to do next?

1. Clean MAF sensor anyway (this seems to be a sensible idea, because it won't cost anything)

2. Replace MAF sensor

3. Replace inlet manifold gasket

4. Replace O2 sensor

5. Replace CAT convertor

6. Something I haven't though of.

Any suggestions please?

[winelight]

OK, I cleaned the MAF sensor wires with carb cleaner and it solved that problem.

[Ash1502]

where abouts is the maf sensor located. ive got a friends aygo with the exact same problem and fault code

[FROSTYBALLS]

See http://www.toyotaownersclub.com/forums/topic/113628-aygo-maf-sensor/