as you can see not a lot . the chips are set in some sort of gel like jelly no obvious issues on visual inspection , it just doesn't work

See https://en.wikipedia.org/wiki/Mass_flow_sensor#Hot_wire_sensor_(MAF)

Have you got a voltage on the bits that stick into the airflow?

Amazing that Land Rover charge £1500 for a GEMS MAF.

David.

I think the two SMD chips are opamps, and that big silvery thing top left is a transistor.

Basically there's a thing like a Wheatstone bridge with a diode and a resistor in the airflow, and a constant-current source to ensure the diode gets hot(tish) so when air blows on it it cools it down decreasing the current flow and causing the output voltage to rise.

dhallworth wrote:

Amazing that Land Rover charge £1500 for a GEMS MAF.

Nah, not that much, only £1137.55 including the VAT (https://www.lrdirect.com/ERR5595-Air-Flow-Meter/) or a mere £897.49 if you are prepared to part ex your duff one (https://rimmerbros.com/Item--i-ERR5595). must admit there's not a lot in it for that money though (and, fortunately, pattern ones work adequately well in a GEMS unlike a Thor that insist on having genuine Bosch).

i did have a prod around with the multi meter but it appeared to be dead . once it entered the board there was nothing , no continuity at the resistors from the inputs , i did not put power across the unit so no voltage readings and i have discarded the unit