Denso 1976040 Mass Air Flow Sensor Replacement - High Performance MAF Sensor for Improved Engine Efficiency | Compatible with Multiple Car Models | Perfect for DIY Auto Repair & Maintenance

This item is now MrTris™ Approved!If you're not sure if you need this, start here: [...] (Or is that what brought you here?) If your '04-'15 turbo Subaru MAF is more than 100k miles old, this is money well-spent. There are charts and graps to tell you that new is better, but, what will mean the most is what you feel : Smoother, improved idle, crispier throttle response; and, if you're like me, elimination of "phantom" knock issues under "normal" driving conditions on the Stage 2 OTS tune.What's in the box: New MAF, with new o-ring. Per instructions on the above link, be careful with the screws. If you're on the east coast and things are rusted and/or seized from salty roads, you would do well to replace them -- they're reasonably cheap. Otherwise, you can get by without needing to. Simply unplug the MAF wiring connector on your airbox, remove the screws (mine were Phillips-head), and pull the old MAF out. Gently push new MAF in, until you feel a positive non-metallic connection; if needed, carefully rotate MAF until the housing's fastener holes line up with your airbox, and re-install screws. Doesn't need to be super tight, just enough to snug it up.Use your AccessPort or Tactrix to reset your ECU, or, if you're still on the stock tune, disconnect your Negative battery terminal and step on the brake pedal for 20 seconds. Reconnect, and restart. Expect the idle to 'hunt' while the ECU relearns the proper parameters, this shouldn't take more than a couple minutes to settle down.Go for a drive and enjoy!UPDATE 02/17/2016: Got tuned at PIA last Halloween, with stellar results, thanks to solid airflow readings from a new MAF. Here we are 90+ days later, everything is still all good. Throttle response and AFRs are ON POINT! Do you and your car some good - Buy a new MAF today!