Maf Sensor Test

[bernb]

Vehicle Focus C-Max 1.6TDCi 2005

Scan testresult shows Mass air flow high 119.41 gms/sec. This is constant at all RPM.

Voltage readings on MAF plug DISCONNECTED ign.on

Pin 1 7.15V, Pin 2 Ground, Pin4 Batt+ 12.17v, Pin 5 11.08V. Pin 3&6 not used.

I do not understand why pin 5 is at approx 1v below B+. This is the MAF signal wire, I expected to get 5v. Pin 1 is IAT signal wire I also expected to read 5v.

Can anyone throw any light on these readings, have you come across this before on any vehicles using this engine i.e Citroen/Peugeot, Mazda etc.

Voltage readings on MAF plug CONNECTED ign.on engine not running.

Pin 1 2.32V, Pin 2 Ground, Pin4 Batt+ 12.15v, Pin 5 10.89V. Pin 3&6 not used.

IAT sensor showing 1 deg.C above ambient (looks ok)

When engine is running the IAT sensor records correctly the B+ pin 4 is at 13.92v(expected) the maf sensor signal at pin5 is 12.42v increase due to alternator output.

The car runs and performs normally I am monitoring fuel consumption but have no figures yet.