The photodiode's voltage drop varies with the temperature and current flowing through it. The typical voltage drop (VBIAS - VREF) across the MAX4007 series is 0.8V, with a guaranteed maximum of 1.1V.

The SMPS switch is connected to the virtual ground of the inverting amplifier when digital input is '1' instead of Vref and switch connects to ground when digital input is '0'. In both the cases the switch is at ground.

To compensate for the effects of headwind 1/2 of the steady wind is added to the Vref (landing speed if you will) in addition to that the full gust factor is added. the total increment shall not be bigger than 20kts (might be Aircraft specific). While actually only headwind matters in this case normally this is disregarded and the full wind speeds are taken to make the calculation easier.

P1401 - DPF EGR Sensor Circuit High Voltage Detected The EGR monitor checks the DPFE sensor signal to the PCM for high voltage. The test fails when the average voltage to the PCM goes to a voltage greater than the maximum calibrated value.

Possible causes:

DPFE circuit open

VREF short to PWR

Damaged DPFE sensor

DPFE circuit short to PWR

SIGNAL RTN circuit open

Damaged PCM

Look at scan data stream for a reading greater than 4.5 volts with the key ON and engine OFF or running. This indicates a hard fault.