E46 323i -Does anyone know if it's ok to unplug the mass airflow sensor and key on?

[bpmgmt]

The Haynes manual says if unplugging the mass airflow sensor (my 2000 323i is throwing the P0101 code) to make sure the key is off. I suspect my sensor is bad because the car won't idle. So, my solution was to unplug the sensor and then run another scan. The thought was if it didn't throw another code with the sensor unplugged, logic would dictate the sensor was bad. This is my first bimmer, so I don't know if turning the key on with it unplugged will cause another issue. Any help is appreciated.

[Raddee]

The DME will throw a code without the MAF, but it will revert to default values in engine control. So; if your car runs badly or won't idle and unplugging your MAF fixes it (you can do it with the ignition turned off if you prefer), you know your MAF is bad. Of course the DME will notice there's no MAF so it will throw a code, but if it runs; you know there's a MAF problem.

[RobertDenali]

Take the idle control valve out first and clean it really well with brakekleen.

The put it back in the car and run it again to see if it fixed your issue.

[MarcoZandrini]

Unplugging the MAF causes the engine computer (DME) to use an overly rich fuel/air mixture. This masks vacuum leaks.

OP, what do you mean when you say the engine doesn’t idle properly? Does the engine’s idle speed vary between 500rpm and 1000rom? You likely have vacuum leaks.

Remove abd ckean the ifle conttol valve. Spraw brake cleaner into the valve and then shake it to distribute the cleaner. The valve needs to rattle when shaken. What tool was used to scan the DME?

[bpmgmt]

Hey Raddee. My scanner won't work without the key on. Thanks for the info

[bpmgmt]

Thanks Robert. I'll try it

[bpmgmt]

Hi Marco. I don't recall the brand. It's just a regular OBD II. And, no it won't idle at all. It tries to start, but then dies like it's out of gas. Another fella suggested that too. The thing is I also lost the gauges at exactly the same time. A new battery fixed the gauges, but not the idle problem.

[bpmgmt]

BTW, I lost the gauges at exactly the same time. A new battery fixed the gauges, but not the idle problem.

[Raddee]

Hey Raddee. My scanner won't work without the key on. Thanks for the info

Testing without MAF obviously needs to happen with the engine running, but what I ment is you can stop the engine, unplug the MAF, start the engine with the MAF unplugged.

[bpmgmt]

Sweet. Thanks again