When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
A mechanic replaced my Mass Air Flow (MAF) unit because the old one was damaged. However, the check engine light is still on, and a diagnostic scan shows "Mass Air Flow too large."
I took it to a trusted mechanic, who found that the previous one didn’t transfer the original MAF sensors to the new unit. He suspects the replacement was a cheap aftermarket part, and the sensors aren’t functioning correctly.
How can I find a reliable replacement (part number) that won’t cause issues? Any recommendations?
ML 320 (W164, 2009 Facelift)
Thanks!
When you replace these you have to disconnect the battery (both negative and positive terminals- not just one). A friend replaced this 3 times until he read the instructions. On the 3rd replacement part he finally disconnected the battery, left it alone for 30 minutes, and problem was gone - just as the instructions that no one bothered to read, said.
Basically your sensor is fine, but because it has the old sensor trim in memory, the difference is too great and it gets an error. 30min with no battery may reset this, otherwise you'll need a scan tool that can access the adaptations (noting you are supposed to reset air filter adaptations each time they are replaced as well).
You're spot on about the possibility of a cheap aftermarket MAF sensor causing issues. These sensors need to be calibrated correctly, and if the replacement part doesn’t match the original specs, it can lead to problems like the "Mass Air Flow too large" code you're seeing. I’d recommend checking if you can find an OEM part number for the MAF sensor, as using a genuine part often helps avoid these types of issues.
If you haven't already, it might also be worth double-checking all the connections and ensuring there are no air leaks in the intake system that could affect the readings. Sometimes, a simple vacuum leak can throw off the MAF sensor readings and trigger the check engine light.
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.
