MAF sensor advice.
 

Hi all, my 2005 crdi went for a check up. All is well except for the Air flow. Mine reads 407 mg/s and it should be 285 mg/s. They took it out and said they were going to clean it. Back in 2 seconds and the reading remained the same. The mechanic was shocked, saying they usually show half the flow , not double it. Any suggestions?