hi all i have my 02 sti and ecu light keeps coming on with 0304 missfire on 4, i have took it to subaru and have said to change maf sensor,but was told by simon at jgm it could be nps sensor before i got subaru to check it,the guy at subaru said it would show missfire on all 4 cylinders if it was neutral position switch sensor.so im asking all would you go for maf as it is 242 pounds !!!!!! also someone posted that a company sold second hand ones that are tested first for 50 pounds,does anyone know who those people are please,any help on this issue would be great thanks

 

I'd always change the cheapest item first, which surely is the NPS? Prob about £80 max brand new from Subaru(?).

Like with any 2nd hand sensor, you take a chance with it lasting for any length of time - bit of a gamble. Personally I'd grit my teeth and always get new items (at least you are ruling them out if the problems remain - so can move on to something else...).

 

You can get the original Subaru MAF sensor for considerably less than that if you shop around.

Don't bother. It looks like a tasty saving but you can't trust a secondhand airflow sensor, no matter how much someone may tell you it's been "tested". You need the reassurance of a new replacement to determine whether or not this is the cause of the fault. If you buy a secondhand one and the issue remains, could it be that the replacement is also faulty? The only way to be certain is with a new part.