FRP_LRS & P0106

[winco]

I am trying to troubleshoot a crank but no start.

The fault code is P0106 and an anomaly when viewing data in Forscan is that the PID FRP_LRS (Fuel Rail Pressure, Low Range Sensor) is showing as 5V as if it is disconnected or unplugged. When I compare with a known good Ecoboost car the FRP_LRS is mid voltage.

Does anyone know what and where the Fuel Rail Pressure, Low Range Sensor is located? Don't be confused with the sensor on the fuel injection fuel rail - this is reading fine.

 

[Handy Andy]

The code you mention is for MAP and Vacuum sensor range issues.

The low pressure range issue is the voltage reading is too low for that sensor - it's asking for more power to the fuel system so the pressure will decrease this voltage output.

So to me, the "Range issue" is from the wiring to the sensor - either the return or the supply (power and return) - this is from the Fuel pressure sender itself.

This Vid might help...

So to verify the sensor is installed the sensor uses an internally-biased termination resistor (a means of diagnostic) to ensure all the lines are in place working - so by showing the 5V on the input from the sensor - the loading "loss" or increased high reading - can be from a poor ground or bad connection at the sensors return wire - lifting this reading to that 5V.

Try putting a variable resistor on the sensor line the output line, from line to ground and see if the input range can be affected and brought back to normal range thru adjustment of resistance to ground from that sensor line. IF you can clear that code by installing a simple resistor - then you know one of those sensors, or the ground lead to them is faulty.

By what I've seen, the Low-pressure side is by the right side of the motor - towards windshield/cowling below that silver thingy with all those lines out of it - you'll need a big wrench about 15/16" (24mm?) to remove it - look and see if you might need a second wrench to help stay the fitting socket while you turn with the other wrench to remove it. Uses 3 wires, this is the one I asked you if you can "backprobe it" with a variable from output leg across rheostat to ground (known ground) to try and clear this error.

Since this is a fuel starvation problem - I am wondering if you have dirt in the orifice of the sensor - and it just needs to be removed and cleaned out.

Try this part number BU5Z-9F972-A (or B) it's an in-line 3pin connector.

California (CA) version shown - smaller orifice than the A or B (which seems A was "made wrong" so B is the currently available one to use - or recommended)

 

[winco]

Don't be confused with the sensor on the fuel injection fuel rail - this is reading fine.

 

[Handy Andy]

I only know of two locations...

​

Here and Here

Since I'm using a Focus and Fiesta - this is a concern. For Ford uses a similar Fuel delivery device in both. (Eco - not all NA 4 cyl) although on the Focus - if they are GDi using a similar fuel system even for NA. (That silver thingy that my local dealership cannot give the true name for)

So do I have the locations correct? Else you'll have to teach the rest of us of what you're up against.