Code P0446 EVAP System Check Engine Light

[airline tech]

If it stays consistent - reset code and it returns - (after resting) - next day (start-up)
Then for me - its failing the (Rationality Check)

Sometimes - the entry conditions can be confusing (chart above)
I read this as (The test will run - Once Per Driving Cycle) only (IF) the entry conditions are met and if they are not met (the test aborts)
Note: They do not list a voltage (in this chart) so the actual pressure reading is the most important


So - at first start - Key On Engine Off
Measure: FTP (Pressure & Voltage) - Note Readings

Install The Funnel - and Note Readings

If stuck at 2.08 Volts - the sensor thinks there is a vacuum on the tank and it expects to see (0-H20) or close to 2.65 volts

Sponsored

 

[rrwhitman]

Thanks for that. I did have the fuel tank pressure PID displayed as well when I was checking the sensor voltage. The software was defaulted to display pressure in Pascals (vice inches of H2O) and I didn't document the value at the time. I can check again but presumably it was indicating a vacuum. From the chart above it seems that +/- 2.0 H2O during the check at start-up (after 4-6 hour soak) will throw the code. I can do more testing after a soak and setting the software to display in H2O. In any case, would you agree that a constant 2.08 Volts from the sensor is enough of an indication of failure to warrant replacement? Thanks again for all of your information!

 

[RangerBill]

Thanks for that. I did have the fuel tank pressure PID displayed as well when I was checking the sensor voltage. The software was defaulted to display pressure in Pascals (vice inches of H2O) and I didn't document the value at the time. I can check again but presumably it was indicating a vacuum. From the chart above it seems that +/- 2.0 H2O during the check at start-up (after 4-6 hour soak) will throw the code. I can do more testing after a soak and setting the software to display in H2O. In any case, would you agree that a constant 2.08 Volts from the sensor is enough of an indication of failure to warrant replacement? Thanks again for all of your information!

At this point, it looks like a replacement of the pressure sensor is required.

 

[rrwhitman]

Thanks everyone. Does anyone have the part number handy for the sensor/tube assembly? I can't seem to locate it online easily.

 

[RangerBill]

Thanks everyone. Does anyone have the part number handy for the sensor/tube assembly? I can't seem to locate it online easily.

Benny @LevittownFordParts.com is a forum sponsor. He should be able to help with the part number.

 

[airline tech]

Yes - with the recent change to the way the IPC is listed - they have - HIDDEN a great deal of information.

We know that this is the Part Number of the sensor - unless it has been revised - but I cannot locate the (Tube Assembly) its part of - do not know how easily it can be (R&R'd) from the preformed tube assy without cracking or creating a leak point, so i think this will come as a (Tube Assembly) - Part Number - Now Hidden from easy view.

 

[airline tech]

This is the detailed parts -IPC - I was looking for as now most IPC diagrams do not show this level of detail

9G271 = Base Part Number - Translates to this Part Number - sometimes it may not show up unless you add the dashes - KB3Z-9G271-A

Confirm with local ford parts counter (if correct) part number

You can find it cheaper for about $125.00 or so

 

[rrwhitman]

I ended up calling a local Ford dealer, got the part number and ordered a new one for delivery tomorrow. The part number is KB3Z-9G271A 'Hose Connecting'. I believe it was hard to look up online because even though the FTP sensor is integral to the assembly, the terms FTP and sensor are not part of the name of the part. With the number it is easy to find.

The KB3Z-9G2711A assembly looks to be two pieces that come apart. The piece on the right, starting with the quick connect in the middle with the visible small green tabs, is the FTP sensor. The part on the left is a vapor valve and the hose goes to the vapor canister.

I just finished removing the old part. After driving the truck to approx. 2 gallons in the tank, I put the front of the truck on ramps, supported the tank in the middle, removed the two straps, and lowered it down far enough to gain access and removed the FTP half of the assembly. I wouldn't call it easy since it is a little awkward to do without a lift (and understanding how the quick connect clips work would have been nice ahead of time), but it is out. Installation should be much, much easier since the two hoses and the electrical connection just press on and latch.

Will update.

Thanks to everyone who share information and their experience on this forum!

 

[airline tech]

I ended up calling a local Ford dealer, got the part number and ordered a new one for delivery tomorrow. The part number is KB3Z-9G271A 'Hose Connecting'. I believe it was hard to look up online because even though the FTP sensor is integral to the assembly, the terms FTP and sensor are not part of the name of the part. With the number it is easy to find.

The KB3Z-9G2711A assembly looks to be two pieces that come apart. The piece on the right, starting with the quick connect in the middle with the visible small green tabs, is the FTP sensor. The part on the left is a vapor valve and the hose goes to the vapor canister.

I just finished removing the old part. After driving the truck to approx. 2 gallons in the tank, I put the front of the truck on ramps, supported the tank in the middle, removed the two straps, and lowered it down far enough to gain access and removed the FTP half of the assembly. I wouldn't call it easy since it is a little awkward to do without a lift (and understanding how the quick connect clips work would have been nice ahead of time), but it is out. Installation should be much, much easier since the two hoses and the electrical connection just press on and latch.

Will update.

Thanks to everyone who share information and their experience on this forum!

Yes the other sensor on that assembly is the (Evap Vapor Blocking Valve)

 

[LevittownFordParts.com]

Sorry were a bit late here but if anyone needs one of these down the line here is a link

https://parts.levittownfordparts.com/oem-parts/ford-hose-connecting-kb3z9g271a

Thanks,
- Benny

 

[rrwhitman]

Thanks, Benny. I'm paying a little more than that, but no shipping and I will have it tomorrow a.m.

 

[airline tech]

While you are there - just for a visual conformation:

Check the connector for the sensor and ensure clean and no corrosion as well as C410 and C408 that feed it.

Pin 1 = FTP Signal - This is providing the reading to the PCM (2.08 Volts)
Pin 2 = Signal Return (circuit) - back to (PCM)
Pin 3 = VREF (5-Volt) Reference (fed from PCM)

I suspect they are good as you do not have any - Low Fuel Pressure issues.
The VREF Feed is shared as well as the Signal Return.

So at minimum - I would check the reading before fully buttoning everything back up and shake the harness across the top of the tank to ensure the reading stays stable and is reading correctly.
NOTE: Connect the Tube before you hit the key on - (fuel pump will prime)

if reading is still (offset) from normal and the FTP sensor connector is good and the harness shake test does not change the reading - move upstream and check connector C410 and C408 for corrosion on the associated pins

C410 - Pins 6-5-7 (high importance to pin 6)
C408 - Pins 23-25-24 (high importance to pin 23)
Pins 6 and 23 - are the signal feed

Basically - trying to eliminate any possible (oh crap) still reads wrong pressure while its still apart and accessible as we have not 100% confirmed bad sensor or bad wiring yet.



If needed the wire harness from C410 up across the tank is replaceable as its a separate harness assembly.
We can also dive into wiring checks if needed, but I suspect its just a bad sensor and just giving options of possibilities if it does not fix the issue.

Ref: C408

Ref: C410

Sponsored