I'd try cleaning the thing first, see if that works.The symptoms of a bad mass air flow sensor include low engine power, poor fuel economy, an engine that won’t start, a check engine light on the dash and a gas smell from the exhaust fumes.Ī bad mass air flow sensor is often the likely culprit if your car isn’t running as it should. And it gets over everything, including the MAF. When people go spraying 5 shots all over it, and then put it back in their car, you bet the engine will suck up the excess. All they need is one quick shot of that oil from about a foot away. Should be easy to replace if its bad.įor the filter, the reason your friends ask if you have a KN is because people typically over oil them. Check to make sure its there, and that its not torn or fully saturated with oil. That is the pre-filter for your crank case ventilation system.

More likely is a problem with your crank case vent or oiling a reusable air filter too much.įor the crank case vent, pull your air filter box apart and remove the engine air filter. Blow-by can happen, but you'd have to have another issue to cause it. MAFs can become contaminated only a few ways. I have a bottle of it in my toolbox at all times. These are the same symptoms that replacing the MAF sensor corrected on my previous Focus (which gave the same Manufacturer Control Fuel Air Metering and System Too Lean codes), so it's just an educated guess. It wasn't until the Manufacturer Control Fuel Air Metering code started showing up intermittently that the vehicle began idling too high, and faltering and stalling at stop lights. I understand that at least one of those is pertaining to the EGR valve/sensors, and I'm open to any suggestions about fixing it, but those codes have been on for a long while with no discernible loss in performance. The two that are normally on are P0401 EGR Flow Insufficient, and P0171 System Too Lean (Bank 1). Can't get the exact code right now as it's not displaying. How should I go about doing that? Since I was planning to replace it in the first place, I guess it's worth a try.Īnd yes, the reason I am asked about K&N is because of the possibility of oil getting on the sensor.Īs for the codes, there is one that is there about half the time I check, and that is 'Manufacturer Control Fuel Air Metering'.

Jet mass air flow sensor problems