I have a MY01 WRX full decat exhaust and gutted uppipe. Recently the fuel consumption has increased by approx 80-100%. The car is throwing a P0420 cel with a AF531v3 map switch rom.

Could the 420 error be causing the excessive fuel consumption? Also ambient temp are 30 deg C.

There are no boost leaks, exhaust leaks. CO at idle is 0.42 and with aircon on co at idle fluctuates between 0.38 and 1.1 over 2 seconds.

 

Faulty Lambda probe possibly

 

Whatever problem you find, let me know - my Sti-8 has the same fuel consumption issues!!!

Alex

 

sounds like ya lambda sensor cost you about £120 plus fittin i fink ... i was lucky i didnt have to pay for mine just an hours labour £44