Quote Originally Posted by mbeach
Not necessarily.
The engine only has one way of determining the correct a/f ratio before the burn -that's the MAF. After the burn you have 2/4 O2 sensors.

If there's a leak (air) between these sensors, the ECU can pick the most likely item. It finds the fault at the O2 sensorS (all of them). Since it is unlikely that both banks would simultaneously go lean, the ECU has the sense to choose the component which measures the incoming air to begin with.

Disconnect the intake tube from the throttle body and I'll bet that you throw a MAF code.
sorry, but that is not how it works.the computer has parameters and when it is outside the parameters it throws a code for that sensor.and the maf is not the only sensor it uses to determine a/f ratio. it also uses the air temp sensor . i agree you would get a check engine light if you disconnect the intake tube but it would not be because it picks the most likely sensor. it would be because it knows there is oxygen coming in (engine cannot run without it) but it is not getting a reading from the maf saying there is air coming in. and you would more than likely get other codes due to the maf not showing air coming in. besides when something is functioning properly before you install something and is not working properly after there is a very big chance (probably 99.9%) that you screwed something up. like pulling the wire to hard. when diagnosing problems you start with the simplest things first. shawn